About | BLOGS | Portfolio | Misc | Recommended | What's New | What's Hot

About | BLOGS | Portfolio | Misc | Recommended | What's New | What's Hot


Bibliography Options Menu

14 Oct 2019 at 01:31
Hide Abstracts   |   Hide Additional Links
Long bibliographies are displayed in blocks of 100 citations at a time. At the end of each block there is an option to load the next block.

Bibliography on: Biofilm


Robert J. Robbins is a biologist, an educator, a science administrator, a publisher, an information technologist, and an IT leader and manager who specializes in advancing biomedical knowledge and supporting education through the application of information technology. More About:  RJR | OUR TEAM | OUR SERVICES | THIS WEBSITE

RJR: Recommended Bibliography 14 Oct 2019 at 01:31 Created: 


Wikipedia: Biofilm A biofilm is any group of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPS). The EPS components are produced by the cells within the biofilm and are typically a polymeric conglomeration of extracellular DNA, proteins, and polysaccharides. Because they have three-dimensional structure and represent a community lifestyle for microorganisms, biofilms are frequently described metaphorically as cities for microbes. Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial and hospital settings. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single-cells that may float or swim in a liquid medium. Biofilms can be present on the teeth of most animals as dental plaque, where they may cause tooth decay and gum disease. Microbes form a biofilm in response to many factors, which may include cellular recognition of specific or non-specific attachment sites on a surface, nutritional cues, or in some cases, by exposure of planktonic cells to sub-inhibitory concentrations of antibiotics. When a cell switches to the biofilm mode of growth, it undergoes a phenotypic shift in behavior in which large suites of genes are differentially regulated.

Created with PubMed® Query: biofilm[title] NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-10-12

Parai D, Banerjee M, Dey P, et al (2019)

Reserpine attenuates biofilm formation and virulence of Staphylococcus aureus.

Microbial pathogenesis pii:S0882-4010(19)30909-X [Epub ahead of print].

This study investigated the effects of reserpine, the main bioactive compound of Rauwolfia serpentina, on biofilm formation and biofilm-associated virulence factors production in a Gram-positive pathogen, Staphylococcus aureus. Crystal violet assay, MTT assay, Congo red binding, CLSM studies were performed to assess the antibiofilm activity. Molecular docking was performed to explain the possible mode of action, catheter model was used to evaluate its application potential and the combinatorial study was performed in search of an improved therapeutic formulation. Reserpine affects biofilm formation, EPS production, biofilm cell viability and virulence factor production. It could eradicate 72.7% biofilm at ½ × MIC dose and could also stop the metabolic activity of 50.6% bacterial cells in a biofilm. Staphylococcus aureus biofilm- and virulence-regulatory proteins like AgrA, AtlE, Bap, IcaA, SarA and SasG were found to interact with reserpine which might lead to the attenuation of its pathogenicity. Reserpine along with other commercial antibiotics could generate a hightened antibiofilm response and could also eradicate a good percentage of bacterial biofilm from a urinary catheter model. These findings suggested reserpine as a good alternative entity to generate new improved therapeutic formulations.

RevDate: 2019-10-12

Dai L, Wu TQ, Xiong YS, et al (2019)

Ibuprofen-mediated potential inhibition of biofilm development and quorum sensing in Pseudomonas aeruginosa.

Life sciences pii:S0024-3205(19)30874-4 [Epub ahead of print].

AIMS: Pseudomonas aeruginosa is one of the leading causes of opportunistic and hospital-acquired infections worldwide, which is frequently linked with clinical treatment difficulties. Ibuprofen, a widely used non-steroidal anti-inflammatory drug, has been previously reported to exert antimicrobial activity with the specific mechanism. We hypothesized that inhibition of P. aeruginosa with ibuprofen is involved in the quorum sensing (QS) systems.

MAIN METHODS: CFU was utilized to assessed the growth condition of P. aeruginosa. Crystal violent staining and acridine orange staining was used to evaluate the biofilm formation and adherence activity. The detection of QS virulence factors such as pyocyanin, elastase, protease, and rhamnolipids were applied to investigation the anti-QS activity of ibuprofen against P. aeruginosa. The production of 3-oxo-C12-HSL and C4-HSL was confirmed by liquid chromatography/mass spectrometry analysis. qRT-PCR was used to identify the QS-related gene expression. Furthermore, we explored the binding effects between ibuprofen and QS-associated proteins with molecular docking.

KEY FINDINGS: Ibuprofen inhibits P. aeruginosa biofilm formation and adherence activity. And the inhibitory effects of ibuprofen on C4-HSL levels were concentration-dependent (p < 0.05), while it has no effect on 3-oxo-C12-HSL. Moreover, ibuprofen attenuates the production of virulence factors in P. aeruginosa (p < 0.05). In addition, the genes of QS system were decreased after the ibuprofen treatment (p < 0.05). Of note, ibuprofen was binding with LuxR, LasR, LasI, and RhlR at high binding scores.

SIGNIFICANCE: The antibiofilm and anti-QS activity of ibuprofen suggest that it can be a candidate drug for the treatment of clinical infections with P. aeruginosa.

RevDate: 2019-10-11

Mugge RL, Lee JS, Brown TT, et al (2019)

Marine biofilm bacterial community response and carbon steel loss following Deepwater Horizon spill contaminant exposure.

Biofouling [Epub ahead of print].

Steel marine structures provide foci of biodiversity when they develop into artificial reefs. Development begins with deposition of a biofilm. The effects of contaminants from oil spills on biofilm microbiomes, microbially-induced corrosion (MIC) and metal loss may impact preservation of marine metal structures. A microcosm experiment exposed biofilms on carbon steel disks (CSDs) to crude oil, dispersant, and dispersed oil to address their impacts on bacterial composition and metal loss and pitting. Biofilm diversity increased over time in all exposures. Community composition in dispersant and dispersed oil treatments deviated from the controls for the duration of a 12-week experiment. As biofilms matured, Pseudomonadaceae increased while Rhodobacteraceae decreased in abundance in dispersed oil treatments compared to the controls and dispersant treatments. Greatest mass loss and deepest pitting on CSDs were observed in dispersed oil treatments, suggesting impacts manifest as a consequence of increased MIC potential on carbon steel.

RevDate: 2019-10-11

Rupel K, Zupin L, Ottaviani G, et al (2019)

Blue laser light inhibits biofilm formation in vitro and in vivo by inducing oxidative stress.

NPJ biofilms and microbiomes, 5:29 pii:102.

Resolution of bacterial infections is often hampered by both resistance to conventional antibiotic therapy and hiding of bacterial cells inside biofilms, warranting the development of innovative therapeutic strategies. Here, we report the efficacy of blue laser light in eradicating Pseudomonas aeruginosa cells, grown in planktonic state, agar plates and mature biofilms, both in vitro and in vivo, with minimal toxicity to mammalian cells and tissues. Results obtained using knock-out mutants point to oxidative stress as a relevant mechanism by which blue laser light exerts its anti-microbial effect. Finally, the therapeutic potential is confirmed in a mouse model of skin wound infection. Collectively, these data set blue laser phototherapy as an innovative approach to inhibit bacterial growth and biofilm formation, and thus as a realistic treatment option for superinfected wounds.

RevDate: 2019-10-11

Bardhan T, Chakraborty M, B Bhattacharjee (2019)

Bactericidal Activity of Lactic Acid against Clinical, Carbapenem-Hydrolyzing, Multi-Drug-Resistant Klebsiella pneumoniae Planktonic and Biofilm-Forming Cells.

Antibiotics (Basel, Switzerland), 8(4): pii:antibiotics8040181.

: Carbapenem resistant Klebsiella pneumoniae has been highlighted to be a critical pathogen by the World Health Organization. The objectives of this study were to assess the efficacy of lactic acid (LA) against planktonic cells and biofilms formed by carbapenem-hydrolyzing K. pneumoniae isolates obtained from the nares of preterm neonates. Time-kill assays with graded percentages of (v/v) LA in water were initially carried out against planktonic cells of a meropenem (MRP)-resistant K. pneumoniae isolate, JNM11.C4. The efficacy parameters such as optimal incubation time and minimum inhibitory concentration were determined by comparing colony-forming unit counts (log(10)CFU). Scanning electron microscopy was used to visualize cell damage. Likewise, JNM11.C4 biofilms were treated with graded series of (v/v) LA. Six carbapenem-hydrolyzing isolates were next used to validate the results. A reduction of 3.6 ± 0.6 log(10) CFU/mL in JNM11.C4 planktonic cells and >3 ± 0.03log(10) CFU/mL in biofilm-forming cells were observed using 0.225% and 2% LA, respectively, after three hours. Similar decreases in viable cell-counts were observed both in the case of planktonic (˃3.6 ± 0.3log(10) CFU/mL) and biofilm-forming cells (3.8 ± 0.3log(10) CFU/mL) across all the six clinical isolates. These results indicate that LA is an effective antimicrobial against planktonic carbapenem-hydrolyzing K. pneumoniae cells and biofilms.

RevDate: 2019-10-10

Bakraoui M, Hazzi M, Karouach F, et al (2019)

Experimental biogas production from recycled pulp and paper wastewater by biofilm technology.

Biotechnology letters pii:10.1007/s10529-019-02735-w [Epub ahead of print].

OBJECTIVE: The main objective of this study is the evaluation of RPPW anaerobic digestion feasibility at laboratory scale under Mesophilic condition. The experiment is conducted using a two-stage biofilm digester of 5 L capacity with mobile support material.

RESULTS: Anaerobic treatment of wastewater from recycled pulp and paper industry in Morocco was tested using a laboratory-scale anaerobic biofilm digester that operated under mesophilic conditions over a 70-day. Chemical oxygen demand (COD) efficiency, volatile and total solid (VS, TS) elimination of the substrate during the process were: 78%, 52% and 48% respectively. The system was stable throughout its operating cycle with an optimum pH (7.24), alkalinity (1750 mg CaCO3/L) and a volatile fatty acid value (760 mg/L). The experimental daily biogas production measured reaches a value of 5 L/day with a composition of 71% methane, 27.6% carbon dioxide, 0.2 oxygen and 7713 ppm of the H2S. The study results show that the anaerobic biofilm reactor is a suitable technique for recycled pulp and paper wastewater (RPPW) treatment. The reactor shows high performances in terms of process stability, removal efficiency (> 70%) and biogas production.

CONCLUSION: Anaerobic digestion is an efficient waste treatment technology that uses natural anaerobic decomposition to reduce the volume of waste while producing biogas. However, research is needed to strengthen microbial metabolism, biochemistry and the functioning of the rector to improve biogas production. The RPPW AD experiment with biofilm digester technology was stable throughout the operation period. The digester knows an overloaded in the last phase of the experiment which leads to an inhibition of biogas production.

RevDate: 2019-10-10

Turner ME, Huynh K, Carney OV, et al (2019)

Genomic instability of TnSMU2 contributes to Streptococcus mutans biofilm development and competence in a cidB mutant.

MicrobiologyOpen [Epub ahead of print].

Streptococcus mutans is a key pathogenic bacterium in the oral cavity and a primary contributor to dental caries. The S. mutans Cid/Lrg system likely contributes to tolerating stresses encountered in this environment as cid and/or lrg mutants exhibit altered oxidative stress sensitivity, genetic competence, and biofilm phenotypes. It was recently noted that the cidB mutant had two stable colony morphologies: a "rough" phenotype (similar to wild type) and a "smooth" phenotype. In our previously published work, the cidB rough mutant exhibited increased sensitivity to oxidative stress, and RNAseq identified widespread transcriptomic changes in central carbon metabolism and oxidative stress response genes. In this current report, we conducted Illumina-based genome resequencing of wild type, cidB rough, and cidB smooth mutants and compared their resistance to oxidative and acid stress, biofilm formation, and competence phenotypes. Both cidB mutants exhibited comparable aerobic growth inhibition on agar plates, during planktonic growth, and in the presence of 1 mM hydrogen peroxide. The cidB smooth mutant displayed a significant competence defect in BHI, which was rescuable by synthetic CSP. Both cidB mutants also displayed reduced XIP-mediated competence, although this reduction was more pronounced in the cidB smooth mutant. Anaerobic biofilms of the cidB smooth mutant displayed increased propidium iodide staining, but corresponding biofilm CFU data suggest this phenotype is due to cell damage and not increased cell death. The cidB rough anaerobic biofilms showed altered structure relative to wild type (reduced biomass and average thickness) which correlated with decreased CFU counts. Sequencing data revealed that the cidB smooth mutant has a unique "loss of read coverage" of ~78 kb of DNA, corresponding to the genomic island TnSMU2 and genes flanking its 3' end. It is therefore likely that the unique biofilm and competence phenotypes of the cidB smooth mutant are related to its genomic changes in this region.

RevDate: 2019-10-09

Liu W, Tian XQ, Wei JW, et al (2019)

Author Correction: BsmR degrades c-di-GMP to modulate biofilm formation of nosocomial pathogen Stenotrophomonas maltophilia.

Scientific reports, 9(1):14778 pii:10.1038/s41598-019-43380-7.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

RevDate: 2019-10-08

Chen H, Luo J, Liu S, et al (2019)

Microbial Methane Conversion to Short-chain Fatty Acids Using Various Electron Acceptors in Membrane Biofilm Reactors.

Environmental science & technology [Epub ahead of print].

Given our vast methane reserves and the forecasted shortage of crude oil in the not too distant future, the conversion of methane into value-added liquid chemicals or fuels would be beneficial. The generated chemicals or fuels could augment the petroleum-dominated chemical market, and also satisfy the increasing demand for transportation fuels. While methane bioconversion to liquid chemicals has just been reported recently, there is limited understanding of the process. This study aims to clarify the potential electron acceptors that could support the process. Here we operated four membrane biofilm reactors (MBfRs) fed with nitrate, nitrite, oxygen at a relatively low rate and oxygen at a relatively high rate, respectively, to study if they can support methane bioconversion to short-chain fatty acids (SCFAs), and the associated microbiological features. All tested electron acceptors facilitated methane bioconversion to SCFAs (ranging from 1.1 to 36.7 mg acetate L-1 d-1, or 3.4 to 114.6 mg acetate d-1 m-2 of biofilm). The carbon efficiency was estimated to be 7.9 ± 1.4% to 148.5 ± 1.3%, with an efficiency higher than 100% suggesting the assimilation of other carbon, very likely CO2, into the products. A low oxygen supply rate of 46.4 ± 2.3 mg O2 d-1 m-2 was found to be the most favourable among all the electron conditions provided according to the SCFAs production rate and also the carbon utilization efficiency. Microbial characterization revealed that completely different communities evolved in the respective reactors, suggesting diverse microbial pathways exist for methane bioconversion into value-added chemicals.

RevDate: 2019-10-08

Diaz PI, AM Valm (2019)

Microbial Interactions in Oral Communities Mediate Emergent Biofilm Properties.

Journal of dental research [Epub ahead of print].

Oral microbial communities are extraordinarily complex in taxonomic composition and comprise interdependent biological systems. The bacteria, archaea, fungi, and viruses that thrive within these communities engage in extensive cell-cell interactions, which are both beneficial and antagonistic. Direct physical interactions among individual cells mediate large-scale architectural biofilm arrangements and provide spatial proximity for chemical communication and metabolic cooperation. In this review, we summarize recent work in identifying specific molecular components that mediate cell-cell interactions and describe metabolic interactions, such as cross-feeding and exchange of electron acceptors and small molecules, that modify the growth and virulence of individual species. We argue, however, that although pairwise interaction models have provided useful information, complex community-like systems are needed to study the properties of oral communities. The networks of multiple synergistic and antagonistic interactions within oral biofilms give rise to the emergent properties of persistence, stability, and long-range spatial structure, with these properties mediating the dysbiotic transitions from health to oral diseases. A better understanding of the fundamental properties of interspecies networks will lead to the development of effective strategies to manipulate oral communities.

RevDate: 2019-10-08

García A, Martínez C, Juárez RI, et al (2019)

Methicillin resistance and biofilm production in clinical isolates of Staphylococcus aureus and coagulase-negative Staphylococcus in México.

Biomedica : revista del Instituto Nacional de Salud, 39(3):513-523.

RevDate: 2019-10-07

Miryala S, Makala H, Yadavali SP, et al (2019)

Disperse red 15 (DR15) impedes biofilm formation of uropathogenic Escherichia coli.

Microbial pathogenesis pii:S0882-4010(19)31120-9 [Epub ahead of print].

Catheter associated urinary tract infection (CAUTI) is a highly prevalent hospital-acquired infection that is predominantly caused by uropathogenic Escherichia coli (UPEC). It adheres on catheter surface using type I pili as the initial step of pathogenesis that progresses to form biofilm. In this study, potential inhibitors against FimH adhesin of type I pili were screened computationally that yielded ten compounds. These were further validated in vitro against adhesion and biofilm formation. The compounds, 1-Amino-4-hydroxyanthraquinone (Disperse Red 15 or DR15) and 4-(4'-chloro-4-biphenylylsulfonylamino) benzoic acid (CB1) impaired adhesion and biofilm formation without inhibiting the planktonic growth. Also, both compounds inhibited cell assemblages like autoaggregation and swarming motility by unknown mechanisms. DR15 was further derivatized into N-(4-hydroxy-9,10-dioxo-9,10-dihydroanthracen-1-yl) undec-10-enamide that self-assembled with linseed oil, which was used as the coating material on urinary Foley catheters. The thin-film coating on the catheter did not leach when incubated in artificial urine and effectively restricted biofilm formation of UPEC. Altogether, the thin-film coating of urinary catheter with DR15 inhibited biofilm formation of UPEC and this application could potentially help to reduce CAUTI incidents in healthcare facilities.

RevDate: 2019-10-07

Silva MOD, J Pernthaler (2019)

Priming of microcystin degradation in carbon-amended membrane biofilm communities is promoted by oxygen limited conditions.

FEMS microbiology ecology pii:5582606 [Epub ahead of print].

Microbial biofilms are an important element of gravity-driven membrane (GDM) filtration systems for decentralized drinking water production. Mature biofilms fed with biomass from the toxic cyanobacterium Microcystis aeruginosa efficiently remove the cyanotoxin microcystin (MC). MC degradation can be 'primed' by prior addition of biomass from a non-toxic M. aeruginosa strain. Increased proportions of bacteria with an anaerobic metabolism in M. aeruginosa-fed biofilms suggest that this 'priming' could be due to higher productivity and the resulting changes in habitat conditions. We, therefore, investigated GDM systems amended with the biomass of toxic [WT] or non-toxic [MUT] M. aeruginosa strains, of diatoms [DT], or with starch solution (ST). After 25 days, these treatments were changed to receiving toxic cyanobacterial biomass. MC degradation established significantly more rapidly in MUT and ST than in DT. Oxygen measurements suggested that this was due to oxygen limited conditions in MUT and ST already prevailing before addition of MC-containing biomass. Moreover, the microbial communities in the initial ST biofilms featured high proportions of facultative anaerobic taxa, whereas aerobes dominated in DT biofilms. Thus, the 'priming' of MC degradation in mature GDM biofilms seems to be related to the prior establishment of oxygen limited conditions mediated by higher productivity.

RevDate: 2019-10-07

Favre L, Ortalo-Magné A, Kerloch L, et al (2019)

Metabolomic and proteomic changes induced by growth inhibitory concentrations of copper in the biofilm-forming marine bacterium Pseudoalteromonas lipolytica.

Metallomics : integrated biometal science [Epub ahead of print].

Copper is an essential element for living cells but this metal is present in some marine environments at such high concentrations that it can be toxic for numerous organisms. In polluted areas, marine organisms may develop specific adaptive responses to prevent cell damage. To investigate the influence of copper on the metabolism of a single organism, a dual approach combining metabolomics and proteomics was undertaken on the biofilm-forming bacterial strain Pseudoalteromonas lipolytica TC8. In order to highlight differential adaptation according to the phenotype, the response of P. lipolytica TC8 to copper stress was studied in planktonic and biofilm culture modes under growth inhibitory copper concentrations. As expected, copper exposure led to the induction of defense and detoxification mechanisms. Specific metabolite and protein profiles were thus observed in each condition (planktonic vs. biofilm and control vs. copper-treated cultures). Copper exposure seems to induce drastic changes in the lipid composition of the bacterial cell membrane and to modulate the abundance of proteins functionally known to be involved in copper cell homeostasis in both planktonic and biofilm culture modes. Much more proteins differentially expressed after copper treatment were observed in biofilms than in planktonic cells, which could indicate a more heterogeneous response of biofilm cells to this metallic stress.

RevDate: 2019-10-06

Liu X, Zhuo S, Jing X, et al (2019)

Flagella act as Geobacter biofilm scaffolds to stabilize biofilm and facilitate extracellular electron transfer.

Biosensors & bioelectronics, 146:111748 pii:S0956-5663(19)30827-9 [Epub ahead of print].

Flagella are widely expressed in electroactive biofilms; however, their actual role is unknown. To understand the role of flagella, two Geobacter sulfurreducens strains (KN400 and PCA, with and without flagella, respectively) were selected. We restored flagellum expression in trans in strain PCA and prevented flagellum expression in strain KN400. Electrochemical results showed that flagellum restoration in strain PCA promoted current generation, while flagellum deletion in strain KN400 impaired current production. However, the expression of conductive pili and outer surface c-type cytochromes was not affected. Further microscopic analyses demonstrated that flagella promoted the formation of thicker biofilms and served as biofilm matrix scaffolds to accommodate more extracellular cytochromes with an orderly arrangement, which increased the electron diffusion rate within the biofilm. Our findings reveal an unprecedented structural role for flagella in stabilizing electroactive biofilms and highlight the importance of cytochromes in electron transfer across biofilms, which will deepen our understanding of biofilm conductivity.

RevDate: 2019-10-05

Shi N, Gao Y, Yin D, et al (2019)

The effect of the sub-minimal inhibitory concentration and the concentrations within resistant mutation window of ciprofloxacin on MIC, swimming motility and biofilm formation of Pseudomonas aeruginosa.

Microbial pathogenesis pii:S0882-4010(19)30433-4 [Epub ahead of print].

OBJECTIVE: To explore the effect of sub-minimal inhibitory concentration (sub-MIC) and concentrations within resistant mutation window (MSW) of ciprofloxacin (CIP) on minimal inhibitory concentration (MIC), swimming motility and biofilm formation of Pseudomonas aeruginosa, and also to investigate the correlation between swimming motility and genes expression of lasI, lasR, rhlI, rhlR and pqsR.

METHODS: The collected strains were incubated under four different concentrations for 5 days. The MIC and mutant prevention concentration (MPC) were measured by the agar dilution method. The diameter of turbid cycle was used to signify the swimming motility. The biofilm formation was measured by the crystal violet stain method. The genes expression of lasI, lasR, rhlI, rhlR and pqsR were measured by RT-PCR.

RESULTS: A total of 11 P. aeruginosa which sensitive to CIP were collected. The incubation within concentrations of MSW made MICs to CIP increased more obviously than under sub-MIC (P < 0.05). The swimming motility showed a trend of being inhibited first and then promoted over time under sub-MIC (P < 0.05), whereas, it was promoted under concentrations within MSW. The biofilm formation was significantly promoted under the concentration of 4×MIC (P < 0.05). Under sub-MIC, the genes expression of rhlR and pqsR had a middle level positive correlation with the promotion of the swimming motility (P < 0.05, r = 0.788 and P < 0.05, r = 0.652, respectively).

CONCLUSIONS: Under the concentration of sub-MIC (0.5×MIC) and the concentrations within MSW (1×MIC, 2×MIC and 4×MIC), the effect of CIP on MICs, swimming motility and biofilm formation of P.aeruginosa was quite different. The genes expression of rhlR and pqsR had a middle level positive correlation with the promotion of the swimming motility.

RevDate: 2019-10-04

Thompson AF, English EL, Nock AM, et al (2019)

Characterizing species interactions that contribute to biofilm formation in a multispecies model of a potable water bacterial community.

Microbiology (Reading, England) [Epub ahead of print].

Microbial biofilms are ubiquitous in drinking water systems, yet our understanding of drinking water biofilms lags behind our understanding of those in other environments. Here, a six-member model bacterial community was used to identify the interactions and individual contributions of each species to community biofilm formation. These bacteria were isolated from the International Space Station potable water system and include Cupriavidus metallidurans, Chryseobacterium gleum, Ralstonia insidiosa, Ralstonia pickettii, Methylorubrum (Methylobacterium) populi and Sphingomonas paucimobilis, but all six species are common members of terrestrial potable water systems. Using reconstituted assemblages, from pairs to all 6 members, community biofilm formation was observed to be robust to the absence of any single species and only removal of the C. gleum/S. paucimobilis pair, out of all 15 possible 2-species subtractions, led to loss of community biofilm formation. In conjunction with these findings, dual-species biofilm formation assays supported the view that the contribution of C. gleum to community biofilm formation was dependent on synergistic biofilm formation with either R. insidiosa or C. metallidurans. These data support a model of multiple, partially redundant species interactions to generate robustness in biofilm formation. A bacteriophage and multiple predatory bacteria were used to test the resilience of the community to the removal of individual members in situ, but the combination of precise and substantial depletion of a single target species was not achievable. We propose that this assemblage can be used as a tractable model to understand the molecular bases of the interactions described here and to decipher other functions of drinking water biofilms.

RevDate: 2019-10-04

Xi Y, Wang Y, Gao J, et al (2019)

Dual Corona Vesicles with Intrinsic Antibacterial and Enhanced Antibiotic Delivery Capabilities for Effective Treatment of Biofilm-Induced Periodontitis.

ACS nano [Epub ahead of print].

Periodontitis is a common disease caused by plaque biofilms, which are important pathogenic factors of many diseases and may be eradicated by antibiotic therapy. However, low dose antibiotic therapy is a complicated challenge for eradiating biofilms as hundreds (even thousands) of times higher concentrations of antibiotics are needed than killing planktonic bacteria. Polymer vesicles may solve these problems via effective antibiotic delivery into biofilms, but traditional single corona vesicles lack the multifunctionalities essential for biofilm eradication. In this paper, we aim to effectively treat biofilm-induced periodontitis using much lower concentrations of antibiotics than traditional antibiotic therapy by designing a multifunctional dual corona vesicle with intrinsic antibacterial and enhanced antibiotic delivery capabilities. This vesicle is co-assembled from two block copolymers, poly(ε-caprolactone)-block-poly(lysine-stat-phenylalanine) [PCL-b-P(Lys-stat-Phe)] and poly(ethylene oxide)-block-poly(ε-caprolactone) [PEO-b-PCL]. Both PEO and P(Lys-stat-Phe) coronas have their specific functions: PEO endows vesicles with protein repelling ability to penetrate extracellular polymeric substances (EPS) in biofilms ('stealthy' coronas), while P(Lys-stat-Phe) provides vesicles with positive charges and broad spectrum intrinsic antibacterial activity. As a result, the dosage of antibiotics can be reduced by 50% when encapsulated in the dual corona vesicles to eradicate Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus) biofilms. Furthermore, effective in vivo treatment has been achieved from a rat periodontitis model, as confirmed by significantly reduced dental plaque, and alleviated inflammation. Overall, this 'stealthy' and antibacterial dual corona vesicle demonstrates a fresh insight for improving the antibiofilm efficiency of antibiotics and combating the serious threat of biofilm-associated diseases.

RevDate: 2019-10-04

Soares Dos Santos DM, Braga AS, Rizk M, et al (2019)

Comparison between micro-computed tomography and transverse microradiography of sound dentine treated with fluorides and demineralized by microcosm biofilm.

European journal of oral sciences [Epub ahead of print].

The study aimed to apply micro-computed tomography (micro-CT) and transverse microradiography (TMR) to measure dentine demineralization and to test the preventive effect of titanium tetrafluoride (TiF4) under microcosm biofilm. Sound dentine specimens from bovine root were treated for 6 h with: (i) 4.0% titanium tetrafluoride (TiF4) varnish [pH 1.0, 2.45% fluoride (F-); (ii) 5.42% sodium fluoride (NaF) varnish (pH 5.0, 2.45% F); (iii) 2% chlorhexidine (CHX) gel (pH 7.0); (iv) placebo varnish (pH 5.0); or (v) no agent (untreated). Dentine specimens were then exposed to human saliva mixed with McBain saliva for 8 h. Thereafter, McBain saliva containing 0.2% sucrose was applied daily, for 5 d, onto dentine specimens to stimulate formation of microcosm biofilm. Although a high correlation was found between the results of both methods regarding integrated mineral loss, the results of the methods did not show good agreement in Bland-Altman plots, with significant biases in calculations of lesion depth. Fluoride varnishes were able to reduce dentine demineralization (P < 0.05), while CHX failed to do so. Fluorides are still the best option to reduce dentine demineralization. Micro-CT may be used to measure dentine mineral loss, but not the lesion depth, for which TMR is superior.

RevDate: 2019-10-04

Yadav S, Sachdev V, Malik M, et al (2019)

Effect of three different compositions of topical fluoride varnishes with and without prior oral prophylaxis on Streptococcus mutans count in biofilm samples of children aged 2-8 years: A randomized controlled trial.

Journal of the Indian Society of Pedodontics and Preventive Dentistry, 37(3):286-291.

Background: Various strategies for controlling caries focus on disrupting the interaction between risk factors. Of these, fluoride varnish has been shown to reduce the colony-forming (CFU) units and water-insoluble extracellular polysaccharide amount. Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and xylitol-containing fluoride varnishes have recently gained importance as caries-protective fluoride varnishes.

Aim: This study aims to assess and compare the reduction in Streptococcus mutans count in biofilm samples after topical application of three different fluoride varnishes and to evaluate the effect of oral prophylaxis prior to fluoride varnish application.

Materials and Methods: Sixty healthy children with no active caries, in the age group of 2-8 years, were randomly divided into Group A = fluoride varnish containing CPP-ACP; Group B = fluoride varnish containing xylitol; and Group C = fluoride varnish with 0.9% difluorosilane; further, the groups were divided into two subgroups, namely A1, B1, and C1 with prior oral prophylaxis and A2, B2, and C2 without oral prophylaxis. Plaque samples were collected at baseline, 1st month, and 3rd month; cultured; and incubated, and CFU/ml was calculated.

Results: Data were compiled, and CFU/ml was analyzed by independent t-test, paired t-test, and one-way ANOVA. There was no statistical difference between the fluoride groups. Furthermore, no statistically significant difference was seen between the subgroups.

Conclusion: Fluoride varnish containing CPP-ACP showed higher reduction in S. mutans count followed by xylitol-containing fluoride varnish and Fluor Protector®. There was no effect of prior oral prophylaxis on the efficacy of fluoride varnish.

RevDate: 2019-10-04

Dundas AA, Sanni O, Dubern JF, et al (2019)

Validating a Predictive Structure-Property Relationship by Discovery of Novel Polymers which Reduce Bacterial Biofilm Formation.

Advanced materials (Deerfield Beach, Fla.) [Epub ahead of print].

Synthetic materials are an everyday component of modern healthcare yet often fail routinely as a consequence of medical-device-centered infections. The incidence rate for catheter-associated urinary tract infections is between 3% and 7% for each day of use, which means that infection is inevitable when resident for sufficient time. The O'Neill Review on antimicrobial resistance estimates that, left unchecked, ten million people will die annually from drug-resistant infections by 2050. Development of biomaterials resistant to bacterial colonization can play an important role in reducing device-associated infections. However, rational design of new biomaterials is hindered by the lack of quantitative structure-activity relationships (QSARs). Here, the development of a predictive QSAR is reported for bacterial biofilm formation on a range of polymers, using calculated molecular descriptors of monomer units to discover and exemplify novel, biofilm-resistant (meth-)acrylate-based polymers. These predictions are validated successfully by the synthesis of new monomers which are polymerized to create coatings found to be resistant to biofilm formation by six different bacterial pathogens: Pseudomonas aeruginosa, Proteus mirabilis, Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli, and Staphylococcus aureus.

RevDate: 2019-10-04

Guilhen C, Miquel S, Charbonnel N, et al (2019)

Colonization and immune modulation properties of Klebsiella pneumoniae biofilm-dispersed cells.

NPJ biofilms and microbiomes, 5:25 pii:98.

Biofilm-dispersal is a key determinant for further dissemination of biofilm-embedded bacteria. Recent evidence indicates that biofilm-dispersed bacteria have transcriptional features different from those of both biofilm and planktonic bacteria. In this study, the in vitro and in vivo phenotypic properties of Klebsiella pneumoniae cells spontaneously dispersed from biofilm were compared with those of planktonic and sessile cells. Biofilm-dispersed cells, whose growth rate was the same as that of exponential planktonic bacteria but significantly higher than those of sessile and stationary planktonic forms, colonized both abiotic and biotic surfaces more efficiently than their planktonic counterparts regardless of their initial adhesion capabilities. Microscopy studies suggested that dispersed bacteria initiate formation of microcolonies more rapidly than planktonic bacteria. In addition, dispersed cells have both a higher engulfment rate and better survival/multiplication inside macrophages than planktonic cells and sessile cells. In an in vivo murine pneumonia model, the bacterial load in mice lungs infected with biofilm-dispersed bacteria was similar at 6, 24 and 48 h after infection to that of mice lungs infected with planktonic or sessile bacteria. However, biofilm-dispersed and sessile bacteria trend to elicit innate immune response in lungs to a lesser extent than planktonic bacteria. Collectively, the findings from this study suggest that the greater ability of K. pneumoniae biofilm-dispersed cells to efficiently achieve surface colonization and to subvert the host immune response confers them substantial advantages in the first steps of the infection process over planktonic bacteria.

RevDate: 2019-10-03

Henning N, Falås P, Castronovo S, et al (2019)

Biological transformation of fexofenadine and sitagliptin by carrier-attached biomass and suspended sludge from a hybrid moving bed biofilm reactor.

Water research, 167:115034 pii:S0043-1354(19)30808-5 [Epub ahead of print].

Laboratory-scale experiments were conducted to investigate the (bio)transformation of the antidiabetic sitagliptin (STG) and the antihistamine fexofenadine (FXF) during wastewater treatment. As inoculum either attached-growth on carriers or suspended sludge from a hybrid moving bed biofilm reactor (HMBBR) was used. Both target compounds were incubated in degradation experiments and quantified via LC-MS/MS for degradation kinetics. Furthermore transformation products (TPs) were analyzed via high resolution mass spectrometry (HRMS). Structural elucidation of the TPs was based on the high resolution molecular ion mass to propose a molecular formula and on MS2 fragmentation to elucidate the chemical structure of the TPs. In total, 22 TPs (9 TPs for STG and 13 TPs for FXF) were detected in the experiments with STG and FXF. For all TPs, chemical structures could be proposed. STG was mainly transformed via amide hydrolysis and conjugation of the primary amine moiety. In contrast, FXF was predominantly transformed by oxidative reactions such as oxidation (dehydrogenation) and hydroxylation. Furthermore, FXF was removed significantly faster in contact with carriers compared to suspended sludge, whereas STG was degraded slightly faster in contact with suspended sludge. Moreover, the primary TP of FXF was also degraded faster in contact with carriers leading to higher proportions of secondary TPs. Thus, the microbial community of both carriers and suspended sludge catalyzed the same primary transformation reactions but the transformation kinetics of FXF and the formation/degradation of FXF TPs were considerably higher in contact with carrier-attached biomass. The primary degradation of both target compounds in pilot- and full-scale conventional activated sludge (CAS) and MBBR reactors reached 42 and 61% for FXF and STG, respectively. Up to three of the identified TPs of FXF and 8 TPs of STG were detected in the effluents of pilot- and full-scale CAS and MBBR.

RevDate: 2019-10-03

Arteaga V, Lamas A, Regal P, et al (2019)

Antimicrobial activity of apitoxin from Apis mellifera in Salmonella enterica strains isolated from poultry and its effects on motility, biofilm formation and gene expression.

Microbial pathogenesis pii:S0882-4010(19)30598-4 [Epub ahead of print].

Salmonella is a major global food-borne pathogen. One of the main concerns related to Salmonella and other food-borne pathogens is their capacity to acquire antimicrobial resistance and produce biofilms. Due to the increased resistance to common antimicrobials used to treat livestock animals and human infections, the discovery of new antimicrobial substances is one of the main challenges in microbiological research. An additional challenge is the development of new methods and substances to inhibit and destruct biofilms. We determined the antimicrobial and antibiofilm activities of apitoxin in 16 Salmonella strains isolated from poultry. In addition, the effect of apitoxin on Salmonella motility and the expression of biofilm- and virulence-related genes was evaluated. The minimum inhibitory concentrations (MIC) of apitoxin ranged from 1,024-256 μg/mL, with 512 μg/mL being the most common. Sub-inhibitory concentrations of apitoxin significantly reduced biofilm formation in 14 of the 16 Salmonella strains tested, with significant increases in motility. MIC concentrations of apitoxin destroyed the pre-formed biofilm by 27.66-68.22% (47.00% ± 10.91). The expression of biofilm- and virulence-related genes and small RNAs was differentially regulated according to the strain and the presence of apitoxin. The transcription of the small RNAs dsrA and csrB, related to antimicrobial resistance, was upregulated in the presence of apitoxin. We suggest that apitoxin is a potential antimicrobial substance that could be used in combination with other substances to develop new drugs and sanitizers against food-borne pathogens.

RevDate: 2019-10-03

Kamiya M, Mori T, Nomura M, et al (2019)

Tradescantia pallida extract inhibits biofilm formation in Pseudomonas aeruginosa.

Nagoya journal of medical science, 81(3):439-452.

Pseudomonas aeruginosa is capable of biofilm formation. In this study, we investigated the effects of aqueous Tradescantia pallida extract on Pseudomonas aeruginosa growth and biofilm formation. Aqueous Tradescantia pallida extracts significantly inhibited both bacterial growth and biofilm formation. However, methanolic Tradescantia pallida extracts inhibited neither. Aqueous Tradescantia pallida extracts were deactivated by heating but were not deactivated by light exposure. The ingredients retained the inhibitory effect on the bacterial growth and biofilm formation after ultrafiltration of aqueous Tradescantia pallida extract. Furthermore, polyphenol-rich Tradescantia pallida extracts inhibited bacterial growth, thus, polyphenols are possible to be an active ingredient. We observed the biofilm by scanning electron microscopy, and quantitative and qualitative differences in the biofilm and cells morphology. Interestingly, the biofilm treated aqueous Tradescantia pallida extracts remained premature. We postulated that premature biofilm formation was due to the inhibition of swarming motility. Indeed, aqueous Tradescantia pallida extracts inhibited swarming motility. These results demonstrate that Peudomonas aeruginosa growth and biofilm formation are inhibited by aqueous Tradescantia pallida extracts.

RevDate: 2019-10-03

Shi YJ, Fang QJ, Huang HQ, et al (2019)

HutZ is required for biofilm formation and contributes to the pathogenicity of Edwardsiella piscicida.

Veterinary research, 50(1):76 pii:10.1186/s13567-019-0693-4.

Edwardsiella piscicida is a severe fish pathogen. Haem utilization systems play an important role in bacterial adversity adaptation and pathogenicity. In this study, a speculative haem utilization protein, HutZEp, was characterized in E. piscicida. hutZEp is encoded with two other genes, hutW and hutX, in an operon that is similar to the haem utilization operon hutWXZ identified in V. cholerae. However, protein activity analysis showed that HutZEp is probably not related to hemin utilization. To explore the biological role of HutZEp, a markerless hutZEp in-frame mutant strain, TX01ΔhutZ, was constructed. Deletion of hutZEp did not significantly affect bacterial growth in normal medium, in iron-deficient conditions, or in the presence of haem but significantly retarded bacterial biofilm growth. The expression of known genes related to biofilm growth was not affected by hutZEp deletion, which indicated that HutZEp was probably a novel factor promoting biofilm formation in E. piscicida. Compared to the wild-type TX01, TX01ΔhutZ exhibited markedly compromised tolerance to acid stress and host serum stress. Pathogenicity analysis showed that inactivation of hutZEp significantly impaired the ability of E. piscicida to invade and reproduce in host cells and to infect host tissue. In contrast to TX01, TX01ΔhutZ was defective in blocking host macrophage activation. The expression of hutZEp was directly regulated by the ferric uptake regulator Fur. This study is the first functional characterization of HutZ in a fish pathogen, and these findings suggested that HutZEp is essential for E. piscicida biofilm formation and contributes to host infection.

RevDate: 2019-10-02

Namgoong S, Jung SY, Han SK, et al (2019)

Clinical experience with surgical debridement and simultaneous meshed skin grafts in treating biofilm-associated infection: an exploratory retrospective pilot study.

Journal of plastic surgery and hand surgery [Epub ahead of print].

Current treatment guidelines for biofilm-associated infections (BAI) recommend repeated sharp/surgical debridement followed by treatment with antimicrobial agents until the wound becomes self-sustaining in terms of a positive wound-healing trajectory. However, complete removal of a biofilm is unlikely, and biofilms reform rapidly. We have treated BAI in patients with chronic diabetic ulcers using a meshed skin graft combined with negative pressure wound therapy (NPWT) immediately after surgical debridement, rather than waiting until the development of clean and healthy granulation tissue; the purpose of this exploratory study was to report the clinical results of this treatment strategy. This retrospective study included 75 patients with chronic diabetic ulcers who were treated for BAI by using surgical debridement, simultaneous meshed skin grafts, and NPWT. Healing time along with the percentage of complete wound closure within 12 weeks were evaluated; bacteria isolated from the wounds and their relation to the wound healing rate were investigated. All 75 wounds healed successfully, and the mean time for complete wound healing was 3.5 ± 1.8 weeks. In particular, 76% of wounds healed uneventfully without graft loss. A mean of 3.3 bacterial colonies/wound were isolated; however, no significant difference in wound healing was observed between the monomicrobial and polymicrobial groups. This exploratory study suggests that surgical debridement and simultaneous meshed skin grafts combined with NPWT may be successfully used to combat BAI in patients with chronic diabetic ulcers. We look forward to larger pivotal studies to confirm or refute these initially promising findings.

RevDate: 2019-10-01

Meyer F, J Enax (2019)

Hydroxyapatite in Oral Biofilm Management.

European journal of dentistry, 13(2):287-290.

Particulate hydroxyapatite, Ca5 (PO4)3 (OH), shows a good biocompatibility and is used as a biomimetic ingredient in dental care formulations due to its similarity to human enamel. Numerous studies show its efficiency, for example, in reducing dentin hypersensitivity, and in the remineralization of enamel and dentin. In addition, oral care products with hydroxyapatite improve periodontal health under in vivo conditions. This review article summarizes data on the effects of hydroxyapatite particles in oral biofilm management. Two databases (PubMed and SciFinder) were searched for studies using specific search terms. In contrast to frequently used antibacterial agents for biofilm control, such as chlorhexidine, stannous salts, and quaternary ammonium salts, hydroxyapatite particles in oral care products lead to a reduction in bacterial attachment to enamel surfaces in situ without having pronounced antibacterial effects or showing unwanted side effects such as tooth discoloration. Furthermore, antibacterial agents might lead to dysbiosis of the oral ecology, which was recently discussed regarding pros and cons. Remarkably, the antiadherent properties of hydroxyapatite particles are comparable to those of the gold standard in the field of oral care biofilm management, chlorhexidine in situ. Although biomimetic strategies have been less well analyzed compared with commonly used antibacterial agents in oral biofilm control, hydroxyapatite particles are a promising biomimetic alternative or supplement for oral biofilm management.

RevDate: 2019-10-01

Fugolin AP, Dobson A, Huynh V, et al (2019)

Antibacterial, Ester-Free Monomers: Polymerization Kinetics, Mechanical Properties, Biocompatibility and Anti-Biofilm Activity.

Acta biomaterialia pii:S1742-7061(19)30660-9 [Epub ahead of print].

OBJECTIVES: Quaternary ammonium (QA) methacrylate monomers have been extensively investigated and demonstrate excellent antibacterial properties. However, the presence of ester bonds makes them prone to degradation in the oral cavity. In this study, ester-free QA monomers based on meth-acrylamides were synthesized and screened for polymerization kinetics, mechanical properties and antibacterial effects.

MATERIALS AND METHODS: Tertiary quaternary ammonium acrylamides (AM) and methacrylamides (MAM) with alkyl side chain lengths of 9 and 14 carbons (C9 and C14) were synthesized and incorporated at 10 wt% into experimental composites based on BisGMA:TEGDMA (1:1), camphorquinone/ethyl-4-dimethylaminobenzoate (0.2/0.8 wt%) and 70 wt% barium glass fillers. Analogous methacrylate versions (MA) were used as controls. Degree of conversion (DC) and rate of polymerization (RP) during photoactivation (800 mW/cm2) were followed in real-time with near-IR. Flexural Strength (FS) and Modulus (E) were measured on 2 × 2 × 25 mm bars in 3-point bending after 24h dry storage and 7-day storage in water at 37°C. Antimicrobial properties and biofilm adhesion (fouling) were evaluated by bioluminescence (Luciferase Assay) and biofilm removal by water spray microjet impingement test, respectively. Cytotoxicity was assessed by MTT assay on dental pulp stem cells (DPSC). Data were analyzed with one-way ANOVA/Tukey's test (α=0.05).

RESULTS: DC was similar for all groups tested (∼70%). Both MAMs and C14-AM presented significantly lower RP. Under dry conditions, FS (110-120 MPa) and E (8-9 GPa) were similar for all groups. After water storage, all materials presented FS/E similar to the control, except for C14-AM (for FS) and C14-MAM (for E), which were lower. All C14 versions were strongly antibacterial, decreasing the titer counts of biofilm by more than two orders of magnitude in comparison to the control. C9 monomers did not present significant antibacterial nor antifouling properties. And biofilms had approximately equivalent adhesion on the C9 composites as on the control. Cytotoxicity did not show significant differences between the MA and AM versions and the control group.

CONCLUSIONS: C14-QA monomers based on methacrylates and meth-acrylamides present strong antibacterial properties, and in general, similar conversion/mechanical properties compared to the methacrylate control.

RevDate: 2019-10-01

Romeu MJ, Alves P, Morais J, et al (2019)

Biofilm formation behaviour of marine filamentous cyanobacterial strains in controlled hydrodynamic conditions.

Environmental microbiology [Epub ahead of print].

Marine biofouling has severe economic impacts and cyanobacteria play a significant role as early surface colonizers. Despite this fact, cyanobacterial biofilm formation studies in controlled hydrodynamic conditions are scarce. In this work, computational fluid dynamics was used to determine the shear rate field on coupons that were placed inside the wells of agitated 12-well microtiter plates. Biofilm formation by three different cyanobacterial strains was assessed at two different shear rates (4 and 40 s-1) which can be found in natural ecosystems and using different surfaces (glass and perspex). Biofilm formation was higher under low shear conditions and differences obtained between surfaces were not always statistically significant. The hydrodynamic effect was more noticeable during the biofilm maturation phase rather than during initial cell adhesion and Optical Coherence Tomography showed that different shear rates can affect biofilm architecture. This study is particularly relevant given the cosmopolitan distribution of these cyanobacterial strains and the biofouling potential of these organisms. This article is protected by copyright. All rights reserved.

RevDate: 2019-10-01

Jiao Y, Tay FR, Niu LN, et al (2019)

Advancing antimicrobial strategies for managing oral biofilm infections.

International journal of oral science, 11(3):28 pii:10.1038/s41368-019-0062-1.

Effective control of oral biofilm infectious diseases represents a major global challenge. Microorganisms in biofilms exhibit increased drug tolerance compared with planktonic cells. The present review covers innovative antimicrobial strategies for controlling oral biofilm-related infections published predominantly over the past 5 years. Antimicrobial dental materials based on antimicrobial agent release, contact-killing and multi-functional strategies have been designed and synthesized for the prevention of initial bacterial attachment and subsequent biofilm formation on the tooth and material surface. Among the therapeutic approaches for managing biofilms in clinical practice, antimicrobial photodynamic therapy has emerged as an alternative to antimicrobial regimes and mechanical removal of biofilms, and cold atmospheric plasma shows significant advantages over conventional antimicrobial approaches. Nevertheless, more preclinical studies and appropriately designed and well-structured multi-center clinical trials are critically needed to obtain reliable comparative data. The acquired information will be helpful in identifying the most effective antibacterial solutions and the most optimal circumstances to utilize these strategies.

RevDate: 2019-10-01

Lopes AA, Yoshii Y, Yamada S, et al (2019)

Roles of lytic transglycosylases in biofilm formation and β-lactam resistance in methicillin-resistant Staphylococcus aureus.

Antimicrobial agents and chemotherapy pii:AAC.01277-19 [Epub ahead of print].

Staphylococcus aureus is responsible for numerous community outbreaks and is one of the most frequent causes of nosocomial infections with significant morbidity and mortality. While the function of lytic transglycosylases (LTs) in relation to cell division, biofilm formation, and antibiotic resistance has been determined for several bacteria, their role in S. aureus remains largely unknown. The only known LTs in S. aureus are immunodominant staphylococcal antigen A (IsaA) and Staphylococcus epidermidis D protein (SceD). Our study demonstrates that, in a strain of methicillin-resistant S. aureus (MRSA), IsaA and SceD contribute differently to biofilm formation and β-lactam resistance. Deletion of isaA, but not sceD, led to decreased biofilm formation. Additionally, in isaA-deleted strains, β-lactam resistance was significantly decreased compared to that of wild-type strains. Plasmid-based expression of mecA, a major determinant of β-lactam resistance in MRSA, in an isaA-deleted strain did not restore β-lactam resistance, demonstrating that the β-lactam susceptibility phenotype is exhibited by isaA mutant regardless of the production level of PBP2a. Overall, our results suggest that IsaA is a potential therapeutic target for MRSA infections.

RevDate: 2019-09-30

Wang X, Kong Y, Zhao H, et al (2019)

Dependence of the Bacillus subtilis biofilm expansion rate on phenotypes and the morphology under different growing conditions.

Development, growth & differentiation [Epub ahead of print].

Biofilms are communities of tightly associated bacteria encased in an extracellular matrix and attached to surfaces of various objects, such as liquid or solid surfaces. Here we use the multi-channel wide field stereo fluorescence microscope to characterize growth of the Bacillus subtilis biofilm, in which the bacterial strain was triple fluorescence labeled for three main phenotypes: motile, matrix producing and sporulating cells. We used the feature point matching approach analyzing time lapse experimental movies to study the biofilm expansion rate. We found that the matrix producing cells dominate the biofilm expansion, at the biofilm edge, the expansion rate of matrix producing cells was almost the same as the velocity of the whole biofilm; however, the motile and sporulating cells were nearly rest. We also found that the biofilm expansion rate evolution relates to cell differentiation and biofilm morphology, and other micro-environments can influence the biofilm growth, such as nutrient, substrate hardness and colony competition. From our work, we get a deeper understanding of the biofilm growth, which can help us to control and to further disperse the biofilm.

RevDate: 2019-09-29

Han C, Goodwine J, Romero N, et al (2019)

Enzyme-encapsulating polymeric nanoparticles: A potential adjunctive therapy in Pseudomonas aeruginosa biofilm-associated infection treatment.

Colloids and surfaces. B, Biointerfaces, 184:110512 pii:S0927-7765(19)30656-3 [Epub ahead of print].

Pseudomonas aeruginosa is a pathogen known to be associated with a variety of diseases and conditions such as cystic fibrosis, chronic wound infections, and burn wound infections. A novel approach was developed to combat the problem of biofilm antibiotic tolerance by reverting biofilm bacteria back to the planktonic mode of growth. This reversion was achieved through the enzymatic depletion of available pyruvate using pyruvate dehydrogenase, which induced biofilm bacteria to disperse from the surface-associated mode of growth into the surrounding environment. However, direct use of the enzyme in clinical settings is not practical as the enzyme is susceptible to denaturation under various storage conditions. We hypothesize that by encapsulating pyruvate dehydrogenase into degradable, biocompatible poly(lactic-co-glycolic) acid nanoparticles, the activity of the enzyme can be extended to deplete available pyruvate and induce dispersion of mature Pseudomonas aeruginosa biofilms. Several particle formulations were attempted in order to permit the use of the smallest dose of nanoparticles while maintaining pyruvate dehydrogenase activity for an extended time length. The nanoparticles synthesized using the optimal formulation showed an average size of 266.7 ± 1.8 nm. The encapsulation efficiency of pyruvate dehydrogenase was measured at 17.9 ± 1.4%. Most importantly, the optimal formulation dispersed biofilms and exhibited enzymatic activity after being stored at 37 °C for 6 days.

RevDate: 2019-09-29

Kart D, Yabanoglu Ciftci S, E Nemutlu (2019)

Altered metabolomic profile of dual-species biofilm: Interactions between Proteus mirabilis and Candida albicans.

Microbiological research, 230:126346 pii:S0944-5013(19)30598-1 [Epub ahead of print].

In this study, we aimed to determine the interspecies interactions between Proteus mirabilis and Candida albicans. Mono and dual-species biofilms were grown in a microtiter plate and metabolomic analysis of the biofilms was performed. The effects of togetherness of two species on the expression levels of candidal virulence genes and urease and swarming activities of P.mirabilis were investigated. The growth of C.albicans was inhibited by P.mirabilis whereas the growth and swarming activity of P.mirabilis were increased by C.albicans. The inhibition of Candida cell growth was found to be biofilm specific. The alteration was not detected in urease activity. The expressions of EFG1, HWP1 and SAP2 genes were significantly down-regulated, however, LIP1 was upregulated by P.mirabilis. In the presence of P.mirabilis carbonhydrates, amino acids, polyamine and lipid metabolisms were altered in C.albicans. Interestingly, the putrescine level was increased up to 230 fold in dual-species biofilm compared to monospecies C.albicans biofilm. To our knowledge, this is the first study to investigate the impact of each microbial pathogen on the dual microbial environment by integration of metabolomic data.

RevDate: 2019-09-28

Caizán-Juanarena L, Krug JR, Vergeldt FJ, et al (2019)

3D biofilm visualization and quantification on granular bioanodes with magnetic resonance imaging.

Water research, 167:115059 pii:S0043-1354(19)30833-4 [Epub ahead of print].

The use of microbial fuel cells (MFCs) for wastewater treatment fits in a circular economy context, as they can produce electricity by the removal of organic matter in the wastewater. Activated carbon (AC) granules are an attractive electrode material for bioanodes in MFCs, as they are cheap and provide electroactive bacteria with a large surface area for attachment. The characterization of biofilm growth on AC granules, however, is challenging due to their high roughness and three-dimensional structure. In this research, we show that 3D magnetic resonance imaging (MRI) can be used to visualize biofilm distribution and determine its volume on irregular-shaped single AC granules in a non-destructive way, while being combined with electrochemical and biomass analyses. Ten AC granules with electroactive biofilm (i.e. granular bioanodes) were collected at different growth stages (3 to 21 days after microbial inoculation) from a multi-anode MFC and T1-weighted 3D-MRI experiments were performed for three-dimensional biofilm visualization. With time, a more homogeneous biofilm distribution and an increased biofilm thickness could be observed in the 3D-MRI images. Biofilm volumes varied from 0.4 μL (day 4) to 2 μL (day 21) and were linearly correlated (R2 = 0.9) to the total produced electric charge and total nitrogen content of the granular bioanodes, with values of 66.4 C μL-1 and 17 μg N μL-1, respectively. In future, in situ MRI measurements could be used to monitor biofilm growth and distribution on AC granules.

RevDate: 2019-09-28

Jain AK, Misra V, Ranjan N, et al (2019)

Speciation, Biofilm Formation and Antifungal Susceptibility of Candida Isolates from Clinically Diagnosed Patient of UTI in a Tertiary Care Hospital.

The Journal of the Association of Physicians of India, 67(9):42-45.

Introduction: The incidence of the urinary tract infections caused by Candida species, are becoming more common. Recently, an increase in the incidence of infection caused by fungi especially non albicans candida species (NAC) has been reported. Several virulence factors like biofilm formation, toxin production and presence of adhesins contribute to its pathogenesis.

Objectives: This study was undertaken to determine species distribution, biofilm formation and in-vitro antifungal susceptibility of candida isolated in our tertiary care hospital.

Method: Eighty seven clinical isolates obtained from urine specimens were subjected to wet mount, Gram's stain and cultured on Sabouraud's Dextrose agar (SDA) medium. Conventional method for yeast identification was done. Biofilm forming ability of each isolate was detected using microtitre plate method. Antifungal susceptibility against posaconazole, amphotericin-B, fluconazole, itraconazole, ketoconazole, 5-flucytosine, voriconazole, and caspofungin was tested using Sensititre® Yeastone® (Trek diagnostic systems).

Results and Discussion: Out of 87 candida isolates, 31.03% (n=27) were C. albicans and 68.97% (n=60) were non albicans candida species (NAC). Among 60 NAC, C. kruseii 29.89% (n=26), C. glabrata 24.14% (n=21), C. tropicalis 14.94% (n=13). Among all isolates, 36.78% (n=32) were biofilm producers and biofilm positivity more among C. albicans 55.56% (n=15) as compared to NAC 28.33% (n=17) (Pvalue<0.002). The maximum positivity was observed with isolates from plastic devices (61.8%). The minimum inhibitory concentrations of all antifungal drugs against all isolates were within susceptible range except for fluconazole which was resistant to C. kruseii.

Conclusion: C. albicans remains the major isolate from urine samples and also biofilm formation as a virulence factor might have a higher significance for C. albicans than for NAC and its ability to form biofilm is intricately linked with ability of organisms to adhere, colonize and subsequently cause infection.

RevDate: 2019-09-28

Yu Z, Li W, S Tan (2019)

Real-time monitoring of the membrane biofouling based on spectroscopic analysis in a marine MBBR-MBR (moving bed biofilm reactor-membrane bioreactor) for saline wastewater treatment.

Chemosphere, 235:1154-1161.

A MBBR-MBR system has been developed with marine microorganisms enriched for saline wastewater treatment in this work, showing high COD and NH3-N removals. The behaviour of fouling-related components (EPS and SMP) has been studied as functions of operating time (40-90 days), salinity (0-30 g/L NaCl) and backflow ratio (0-300%, from MBR to MBBR). High biodegradability of the MBBR-MBR at optimal conditions can induce more biodegradation of humic acid-like (λex/λem: 350nm/430 nm) and fulvic acid-like (260nm/445 nm) molecules to soluble microbial by-product-like molecules (275nm/325 nm), reducing the membrane biofouling rate. The biodegradation process is suggested by the excitation-emission matrix (EEM) images. In the study of sudden salinity shock, results show that real-time monitoring the concentration of biofoulants is more effective (operative time extended by 60%) than monitoring the transmembrane pressure (operative time extended by 33%) to prevent membrane fouling. Due to an early warning from the real-time monitoring, the coming membrane-fouling is predictable and the operating conditions, such as backflow ratio, can be changed to minimize the biofouling rate.

RevDate: 2019-09-27

Oliveira GS, Lopes DRG, Andre C, et al (2019)

Multispecies biofilm formation by the contaminating microbiota in raw milk.

Biofouling [Epub ahead of print].

Biofilms can be formed on the surfaces of dairy processing equipment and are a potential source of product contamination. This study evaluated the diversity of multispecies biofilms formed on stainless steel (SS) due to the contaminating microbiota in raw milk. Samples of raw milk were used: one was fresh milk and the other maintained in refrigerated bulk tanks for up to 48 h. The mesophilic aerobic contamination was ∼104 CFU ml-1 in fresh milk and 106 CFU ml-1 in bulk milk. SS coupons were kept immersed in the milk at 7 ±2 °C for 10 days, and every two days, the raw milk was changed for samples of the same origin collected on the current day. After incubation for 10 days, sessile cells in the biofilm reached 105 CFU cm-2 in the presence of fresh milk, and 106 CFU cm-2 in the presence of bulk milk. The genetic diversity analysis showed that Gammaproteobacteria and Bacilli predominated in the biofilms throughout the incubation of both milk samples and these biofilms showed a reduction in diversity over time. The main classes of bacteria found in these biofilms have representatives of great importance since many of them have spoilage potential.

RevDate: 2019-09-26

Kurt A, Cilingir A, Bilmenoglu C, et al (2019)

Effect of different polishing techniques for composite resin materials on surface properties and bacterial biofilm formation.

Journal of dentistry pii:S0300-5712(19)30195-2 [Epub ahead of print].

OBJECTIVES: Both direct and indirect techniques are used for composite resin material (CRM) restorations. Polishing processes are needed in both techniques after intraoral adjustment. However, it is unclear as to which polishing technique should be preferred with respect to decreasing biofilm. The purpose of thisin vitro study was to evaluate the surface properties and Streptococcus mutans biofilm formation on direct and indirect CRMs after using different polishing techniques.

METHODS: Two CRMs (direct and indirect) and four polishing techniques (aluminium oxide discs, diamond polishing paste, aluminium oxide polishing paste, and silicon carbide brush) were evaluated. The specimens were prepared for taking scanning electron microscopy images (n = 2) and determining surface roughness, surface free energy, and bacterial biofilm formation (BBF) with colony-forming unit counting and confocal laser scanning microscopy assays (n = 7). The data were analysed using two-way analysis of variance with Bonferroni as a post hoc test and Pearson's correlation (p < .05).

RESULTS: The surface roughness values in the control group were higher than those in the diamond polishing paste group (p = 0.025), but the values in the aluminium oxide polishing paste and silicon carbide brush groups were comparable with those in the control group (p = 0.156 and p = 1.000, respectively). The highest surface free energy values were recorded in the silicon carbide brush group (p < 0.001), whereas there were no differences found among the other groups (p > 0.05). The highest BBF was seen in the silicon carbide brush (p < 0.001) and direct CRM (p < 0.001) groups.

CONCLUSION: BBF on the surface of direct CRMs differed from that on indirect CRMs after polishing the surface. The tested polishing techniques significantly influenced surface properties and BBF.

CLINICAL SIGNIFICANCE: In situations that require the intraoral adjustment of CRMs, polishing with a diamond polishing paste seems to be a good option to polish the surface of both direct and indirect CRMs because the diamond polishing paste results better in terms of decreasing biofilm formation and improving surface properties.

RevDate: 2019-09-26

Horváthová T, U Bauchinger (2019)

Biofilm Improves Isopod Growth Independent of the Dietary Cellulose Content.

Physiological and biochemical zoology : PBZ, 92(6):531-543.

Cellulose is an abundant source of carbon, accounting for more than 50% of foliage and 90% of woody tissues of plants. Despite the diversity of species that include living or dead plant tissue in their diets, the ability to digest cellulose through self-produced enzymatic machinery is considered rare in the animal kingdom. The majority of animals studied to date rely on the cellulolytic activity of symbiotic microorganisms in their digestive tract, with some evidence for a complementary action of endogenous cellulases. Terrestrial isopods have evolved a lifestyle including feeding on a lignocellulose diet. Whether isopods utilize both external and internal cellulases for digestion of a diet is still not understood. We experimentally manipulated the content of cellulose (30%, 60%, or 90%) and the amount of biofilm (small or large) in the offered food source and quantified growth and cellulolytic activity in the gut of the isopod Porcellio scaber. The presence of a visible biofilm significantly promoted isopod growth, regardless of the cellulose content in the diet. The activity of gut cellulases was not significantly affected by the amount of biofilm or the cellulose content. Our results do not support a significant contribution of either ingested or host enzymes to cellulose utilization in P. scaber. Cellulose might not represent a key nutrient for isopods and does not seem to affect the nutritional value of the diet-associated biofilm. We propose that it is the biofilm community that determines the quality of plant diet in terrestrial isopods and potentially also in other detrital plant feeders.

RevDate: 2019-09-26

Lee JK, Mereuta L, Luchian T, et al (2019)

Antimicrobial peptide HPA3NT3-A2 effectively inhibits biofilm formation in mice infected with drug-resistant bacteria.

Biomaterials science [Epub ahead of print].

Bacterial biofilms formed through secretion of extracellular polymeric substances (EPS) have been implicated in many serious infections and can increase antibiotic resistance by a factor of more than 1000. Here, we examined the abilities of the antimicrobial peptide HPA3NT3-A2 to inhibit and reduce biofilm formation, eliminate EPS, and suppress inflammation in mice infected with clinical isolates of drug-resistant Pseudomonas aeruginosa strains. HPA3NT3-A2 was developed from a desirable analogue peptide, HPA3NT3, derived from residues 2-20 of the Helicobacter pylori ribosomal protein L1. HPA3NT3-A2 showed stronger activity against planktonic cells (MIC: 8 μM) compared to ciprofloxacin or tobramycin (>512 μM), and a favorable minimum biofilm inhibition and elimination concentration. This peptide also neutralized LPS; decreased levels of EPS; inhibited the production of pro-inflammatory cytokines in the lung, kidney, and spleen; decreased white blood cell counts; and increased survival among infected mice.

RevDate: 2019-09-25

Sommer R, Rox K, Wagner S, et al (2019)

Anti-Biofilm Agents against Pseudomonas aeruginosa: a Structure-Activity Relationship Study of C-Glycosidic LecB Inhibitors.

Journal of medicinal chemistry [Epub ahead of print].

Biofilm formation is a key mechanism of antimicrobial resistance. We have recently reported two classes of orally bioavailable C-glycosidic inhibitors of the Pseudomonas aeruginosa lectin LecB with anti-biofilm activity. They proved efficient in target binding, were metabolically stable, non-toxic, selective and potent in inhibiting formation of bacterial biofilm. Here, we designed and synthesized 6 new carboxamides and 24 new sulfonamides for a detailed structure-activity-relationship for two clinically representative LecB variants. Sulfonamides generally showed higher inhibition compared to carboxamides which was rationalized based on crystal structure analyses. Substitutions at the thiophenesulfonamide increased binding through extensive contacts with a lipophilic protein patch. These metabolically stable compounds showed a further increase in potency towards the target and in biofilm inhibition assays. In general, we established the structure-activity relationship for these promising anti-biofilm agents and showed that modification of the sulfonamide residue bears future optimization potential.

RevDate: 2019-09-25

Kaldhone PR, Carlton A, Aljahdali N, et al (2019)

Evaluation of Incompatibility Group I1 (IncI1) Plasmid-Containing Salmonella enterica and Assessment of the Plasmids in Bacteriocin Production and Biofilm Development.

Frontiers in veterinary science, 6:298.

Mobile genetic elements, such as plasmids, can potentially increase the ability of bacteria to infect and persist in vertebrate host cells. IncI1 plasmids are widely distributed in Salmonella from food animal sources and associated with clinically important strains. These plasmids often encode antimicrobial resistance; however, little is known about their impact on the virulence of Salmonella strains. To assess the potential impact of the plasmids on virulence, 43 IncI1-positive Salmonella isolates from human and animal sources were subjected to whole genome sequence (WGS) analyses and evaluated for their abilities to invade and persist for 48 h in Caco-2 human intestinal epithelial cells, form biofilms and encode bacteriocins. Draft WGS data were submitted to predict the presence of virulence and antimicrobial resistance genes, plasmid replicon types present, conduct plasmid multilocus sequence typing (pMLST), and core genome MLST (cgMLST) in the isolates. Caco-2 cells were infected with Salmonella strains and incubated for both one and 48 h for the invasion and persistence assays, respectively. Additionally, Salmonella isolates and IncI1 plasmid carrying transconjugants (n = 12) generated in Escherichia coli were assessed for their ability to produce biofilms and bacteriocin inhibition of growth of other bacteria. All Salmonella isolates infected Caco-2 cells and persisted in the cells at 48 hrs. Persistent cell counts were observed to be significantly higher than invasion assay cell counts in 26% of the isolates. Among the IncI1 plasmids, there were 18 pMLST types. Nearly 35% (n = 15) of Salmonella isolates produced biofilms; however, none of the IncI1-positive transconjugants produced increased biofilms compared to the recipient. Approximately 65% (n = 28) of isolates and 67% (n = 8) of IncI1-positive transconjugants were able to inhibit growth of at least one E. coli strain; however, none inhibited the growth of strains from species other than E. coli. The study characterized IncI1 positive Salmonella isolates and provided evidence about the potential contributions of IncI1 plasmids virulence phenotypes and areas where they do not. These findings should allow for more focused efforts to assess the impact of plasmids on bacterial pathophysiology and human health.

RevDate: 2019-09-25

Willett JLE, Ji MM, GM Dunny (2019)

Exploiting biofilm phenotypes for functional characterization of hypothetical genes in Enterococcus faecalis.

NPJ biofilms and microbiomes, 5:23 pii:99.

Enterococcus faecalis is a commensal organism as well as an important nosocomial pathogen, and its infections are typically linked to biofilm formation. Nearly 25% of the E. faecalis OG1RF genome encodes hypothetical genes or genes of unknown function. Elucidating their function and how these gene products influence biofilm formation is critical for understanding E. faecalis biology. To identify uncharacterized early biofilm determinants, we performed a genetic screen using an arrayed transposon (Tn) library containing ~2000 mutants in hypothetical genes/intergenic regions and identified eight uncharacterized predicted protein-coding genes required for biofilm formation. We demonstrate that OG1RF_10435 encodes a phosphatase that modulates global protein expression and arginine catabolism and propose renaming this gene bph (biofilm phosphatase). We present a workflow for combining phenotype-driven experimental and computational evaluation of hypothetical gene products in E. faecalis, which can be used to study hypothetical genes required for biofilm formation and other phenotypes of diverse bacteria.

RevDate: 2019-09-25

El-Ezmerli NF, RL Gregory (2019)

Effect of nicotine on biofilm formation of Streptococcus mutans isolates from smoking and non-smoking subjects.

Journal of oral microbiology, 11(1):1662275 pii:1662275.

Objectives: To investigate effects of nicotine on biofilm formation of Streptococcus mutans isolates from oral washes of smoker and non-smoker human subjects. Materials and methods: This study was conducted using 60 S. mutans isolates with three S. mutans isolates collected from oral washes of ten smoking subjects and ten from non-smoking subjects. Biofilm was formed by culturing each S. mutans strain (10 μl) in 190 μl of TSB supplemented with 1% sucrose (TSBS) containing 0, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0, and 32.0 mg/ml of nicotine for 24 h in 5% CO2 at 37°C in 96 well microtiter plates. The absorbance values of biofilm were measured at 490 nm in a microplate spectrophotometer. Results: There was a significant effect (p-value < 0.05) of nicotine concentrations and smoking on the growth of biofilm, planktonic cells, and total absorbance, for all strains of S. mutans. Isolates from smokers had significantly more biofilm at 0-16 mg/ml of nicotine compared to those from non-smokers (p-value < 0.0001). Conclusion: S. mutans smoker isolates are more affected by high nicotine concentrations than non-smoker isolates. Clinical Relevance: The use of nicotine products increases the growth of S. mutans and may place tobacco users at risk for dental decay.

RevDate: 2019-09-25

Selvaraj A, Jayasree T, Valliammai A, et al (2019)

Myrtenol Attenuates MRSA Biofilm and Virulence by Suppressing sarA Expression Dynamism.

Frontiers in microbiology, 10:2027.

Methicillin-resistant Staphylococcus aureus (MRSA) is a deleterious human pathogen responsible for severe morbidity and mortality worldwide. The pathogen has attained high priority in the World Health Organization (WHO) - Multidrug-resistant (MDR) pathogens list. Emerging MDR strains of S. aureus are clinically challenging due to failure in conventional antibiotic therapy. Biofilm formation is one of the underlying mechanisms behind the antibiotic resistance. Hence, attenuating biofilm formation has become an alternative strategy to control persistent infections. The current study is probably the first that focuses on the antibiofilm and antivirulence potential of myrtenol against MRSA and its clinical isolates. Myrtenol exhibited a concentration-dependent biofilm inhibition without causing any harmful effect on cell growth and viability. Further, microscopic analysis validated the biofilm inhibitory efficacy of myrtenol against MRSA. In addition, myrtenol inhibited the synthesis of major virulence factors including slime, lipase, α-hemolysin, staphyloxanthin and autolysin. Inhibition of staphyloxanthin in turn sensitized the MRSA cells to healthy human blood and hydrogen peroxide (H2O2). Notably, myrtenol treated cells were deficient in extracellular DNA (eDNA) mediated autoaggregation as eDNA releasing autolysis was impaired by myrtenol. Biofilm disruptive activity on preformed biofilms was observed at concentrations higher than minimum biofilm inhibitory concentration (MBIC) of myrtenol. Also, the non-cytotoxic effect of myrtenol on human peripheral blood mononuclear cell (PBMC) was evidenced by trypan blue and Alamar blue assays. Transcriptional analysis unveiled the down-regulation of global regulator sarA and sarA mediated virulence genes upon myrtenol treatment, which is well correlated with results of phenotypic assays. Thus, the results of the present study revealed the sarA mediated antibiofilm and antivirulence potential of myrtenol against MRSA.

RevDate: 2019-09-25

Bottagisio M, Soggiu A, Piras C, et al (2019)

Proteomic Analysis Reveals a Biofilm-Like Behavior of Planktonic Aggregates of Staphylococcus epidermidis Grown Under Environmental Pressure/Stress.

Frontiers in microbiology, 10:1909.

Prosthetic joint replacement failure has a huge impact on quality of life and hospitalization costs. A leading cause of prosthetic joint infection is bacteria-forming biofilm on the surface of orthopedic devices. Staphylococcus epidermidis is an emergent, low-virulence pathogen implicated in chronic infections, barely indistinguishable from aseptic loosening when embedded in a mature matrix. The literature on the behavior of quiescent S. epidermidis in mature biofilms is scarce. To fill this gap, we performed comparative analysis of the whole proteomic profiles of two methicillin-resistant S. epidermidis strains growing in planktonic and in sessile form to investigate the molecular mechanisms underlying biofilm stability. After 72-h culture of biofilm-forming S. epidermidis, overexpression of proteins involved in the synthesis of nucleoside triphosphate and polysaccharides was observed, whereas planktonic bacteria expressed proteins linked to stress and anaerobic growth. Cytological analysis was performed to determine why planktonic bacteria unexpectedly expressed proteins typical of sessile culture. Images evidenced that prolonged culture under vigorous agitation can create a stressful growing environment that triggers microorganism aggregation in a biofilm-like matrix as a mechanism to survive harsh conditions. The choice of a unique late time point provided an important clue for future investigations into the biofilm-like behavior of planktonic cells. Our preliminary results may inform comparative proteomic strategies in the study of mature bacterial biofilm. Finally, there is an increasing number of studies on the aggregation of free-floating bacteria embedded in an extracellular matrix, prompting the need to gain further insight into this mode of bacterial growth.

RevDate: 2019-09-25

Valliammai A, Sethupathy S, Priya A, et al (2019)

5-Dodecanolide interferes with biofilm formation and reduces the virulence of Methicillin-resistant Staphylococcus aureus (MRSA) through up regulation of agr system.

Scientific reports, 9(1):13744 pii:10.1038/s41598-019-50207-y.

Methicillin resistant Staphylococcus aureus (MRSA) is a predominant human pathogen with high morbidity that is listed in the WHO high priority pathogen list. Being a primary cause of persistent human infections, biofilm forming ability of S. aureus plays a pivotal role in the development of antibiotic resistance. Hence, targeting biofilm is an alternative strategy to fight bacterial infections. The present study for the first time demonstrates the non-antibacterial biofilm inhibitory efficacy of 5-Dodecanolide (DD) against ATCC strain and clinical isolates of S. aureus. In addition, DD is able to inhibit adherence of MRSA on human plasma coated Titanium surface. Further, treatment with DD significantly reduced the eDNA synthesis, autoaggregation, staphyloxanthin biosynthesis and ring biofilm formation. Reduction in staphyloxanthin in turn increased the susceptibility of MRSA to healthy human blood and H2O2 exposure. Quantitative PCR analysis revealed the induced expression of agrA and agrC upon DD treatment. This resulted down regulation of genes involved in biofilm formation such as fnbA and fnbB and up regulation of RNAIII, hld, psmα and genes involved in biofilm matrix degradation such as aur and nuc. Inefficacy of DD on the biofilm formation of agr mutant further validated the agr mediated antibiofilm potential of DD. Notably, DD was efficient in reducing the in vivo colonization of MRSA in Caenorhabditis elegans. Results of gene expression studies and physiological assays unveiled the agr mediated antibiofilm efficacy of DD.

RevDate: 2019-09-25

Qi M, Li X, Sun X, et al (2019)

Novel nanotechnology and near-infrared photodynamic therapy to kill periodontitis-related biofilm pathogens and protect the periodontium.

Dental materials : official publication of the Academy of Dental Materials pii:S0109-5641(19)30847-4 [Epub ahead of print].

OBJECTIVE: Periodontal tissue destruction and tooth loss are increasingly a worldwide problem as the population ages. Periodontitis is caused by bacterial infection and biofilm plaque buildup. Therefore, the objectives of this study were to: (1) develop a near-infrared light (NIR)-triggered core-shell nanostructure of upconversion nanoparticles and TiO2 (UCNPs@TiO2), and (2) investigate its inhibitory effects via antibacterial photodynamic therapy (aPDT) against periodontitis-related pathogens.

METHODS: The core β-NaYF4:Yb3+,Tm3+ were synthesized via thermal decomposition and further modified with the TiO2 shell via a hydrothermal method. The core-shell structure and the upconversion fluorescence-induced aPDT treatment via 980nm laser were studied. Three periodontitis-related pathogens Streptococcus sanguinis (S. sanguinis), Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nucleatum (F. nucleatum) were investigated. The killing activity against planktonic bacteria was detected by a time-kill assay. Single species 4-day biofilms on dentin were tested by live/dead staining, colony-forming units (CFU), and metabolic activity.

RESULTS: The hexagonal shaped UCNPs@TiO2 had an average diameter of 39.7nm. UCNPs@TiO2 nanoparticles had positively charged (+12.4mV) surface and were biocompatible and non-cytotoxic. Under the excitation of NIR light (980nm), the core NaYF4:Yb3+,Tm3+ UCNPs could emit intense ultraviolet (UV) light, which further triggered the aPDT function of the shell TiO2 via energy transfer, thereby realizing the remarkable antibacterial effects against planktons and biofilms of periodontitis-associated pathogens. NIR-triggered UCNPs@TiO2 achieved much greater reduction in biofilms than control (p<0.05). Biofilm CFU was reduced by 3-4 orders of magnitude via NIR-triggered aPDT, which is significantly greater than that of negative control and commercial aPDT control groups. The killing efficacy of UCNPs@TiO2-based aPDT against the three species was ranked to be: S. sanguinis
SIGNIFICANCE: Upconversion fluorescence-based aPDT achieved strong inhibiting effects against all three species of periodontitis-related pathogens. This novel nanotechnology demonstrated a high promise to inhibit periodontitis, with exciting potential to combat other oral infectious diseases such as deep endodontic infections.

RevDate: 2019-09-25

de Freitas LM, Lorenzón EN, Cilli EM, et al (2019)

Photodynamic and peptide-based strategy to inhibit Gram-positive bacterial biofilm formation.

Biofouling, 35(7):742-757.

The self-produced extracellular polymeric matrix of biofilms renders them difficult to eliminate once they are established. This makes the inhibition of biofilm formation key to successful treatment of biofilm infection. Antimicrobial photodynamic therapy (aPDT) and antimicrobial peptides offer a new approach as antibiofilm strategies. In this study sub-lethal doses of aPDT (with chlorin-e6 (Ce6-PDT) or methylene blue (MB-PDT)) and the peptides AU (aurein 1.2 monomer) or (AU)2K (aurein 1.2 C-terminal dimer) were combined to evaluate their ability to prevent biofilm development by Enterococcus faecalis. Biofilm formation was assessed by resazurin reduction, confocal microscopy, and infrared spectroscopy. All treatments successfully prevented biofilm development. The (AU)2K dimer had a stronger effect, both alone and combined with aPDT, while the monomer AU had significant activity when combined with Ce6-PDT. Additionally, it is shown that the peptides bind to the lipoteichoic acid of the E. faecalis cell wall, pointing to a possible key mechanism of biofilm inhibition.

RevDate: 2019-09-25

Werner BG, Wu JY, JM Goddard (2019)

Antimicrobial and antifouling polymeric coating mitigates persistence of Pseudomonas aeruginosa biofilm.

Biofouling, 35(7):785-795.

Food wasted due to food spoilage remains a global challenge to the environmental sustainability and security of food supply. In food manufacturing, post-processing contamination of food can occur due to persistent bacterial biofilms, which can be resistant to conventional cleaning and sanitization. The objective was to characterize the efficacy of a polymeric coating in reducing Pseudomonas aeruginosa biofilm establishment and facilitating its removal. Viable cell density of a 48 h biofilm was reduced by 2.10 log cfu cm-2 on the coated surface, compared to native polypropylene. Confocal laser scanning and electron microscopy indicated reductions in mature biofilm viability and thickness on the coated material. The antifouling coating improved cleanability, with ∼2.5 log cfu cm-2 of viable cells remaining after 105 min cleaning by water at 65 °C, compared to 4.5 log cfu cm-2 remaining on native polypropylene. Such coatings may reduce the persistence of biofilms in food processing environments, in support of reducing food spoilage and waste.

RevDate: 2019-09-24

Hoque J, Ghosh S, Paramanandham K, et al (2019)

Charge-Switchable Polymeric Coating Kills Bacteria and Prevents Biofilm Formation In vivo.

ACS applied materials & interfaces [Epub ahead of print].

Preventing bacterial biofilm formation on medical devices and implants in vivo still remains a daunting task. Current antibacterial coatings to combat implant-associated infections are generally composed of toxic metals or non-degradable polymers and involve multistep surface modifications. Here we present a charge-switchable antibacterial and antibiofilm coating based on water-insoluble cationic hydrophobic polymers that are soluble in organic solvents and can be non-covalently coated onto different surfaces. Towards this, a library of quaternary polyethylenimine (QPEI) polymers with amide or ester group in their pendant alkyl chain was developed. These QPEIs are shown to hydrolyze from active cationic to non-toxic zwitterionic polymers under acidic or enzymatic conditions. Notably polymers with both zwitterionic and cationic groups, obtained upon incomplete hydrolysis of QPEIs, are shown to retain their antibacterial activity with much lower toxicity towards mammalian cells. Furthermore the zwitterionic polymer, fully hydrolyzed product of the QPEIs, is shown to be non-toxic to mammalian cells in vitro as well as in vivo. The QPEIs-coated surfaces are shown to kill bacteria and prevent formation of biofilm. In an in vivo mice model, the QPEIs-coated medical grade catheter is shown to reduce methicillin-resistant Staphylococcus aureus (MRSA) contamination both on the catheter surface and in the adjacent tissues (99.99% reduction compared to non-coated catheter). Additionally, biofilm formation is inhibited on the catheter surface with negligible inflammation in the adjacent tissue. The above results thus highlight the importance of these polymers to be used as effective antibacterial coatings in biomedical applications.

RevDate: 2019-09-24

Kowalski CH, Kerkaert JD, Liu KW, et al (2019)

Fungal biofilm morphology impacts hypoxia fitness and disease progression.

Nature microbiology pii:10.1038/s41564-019-0558-7 [Epub ahead of print].

Microbial populations form intricate macroscopic colonies with diverse morphologies whose functions remain to be fully understood. Despite fungal colonies isolated from environmental and clinical samples revealing abundant intraspecies morphological diversity, it is unclear how this diversity affects fungal fitness and disease progression. Here we observe a notable effect of oxygen tension on the macroscopic and biofilm morphotypes of the human fungal pathogen Aspergillus fumigatus. A hypoxia-typic morphotype is generated through the expression of a subtelomeric gene cluster containing genes that alter the hyphal surface and perturb interhyphal interactions to disrupt in vivo biofilm and infection site morphologies. Consequently, this morphotype leads to increased host inflammation, rapid disease progression and mortality in a murine model of invasive aspergillosis. Taken together, these data suggest that filamentous fungal biofilm morphology affects fungal-host interactions and should be taken into consideration when assessing virulence and host disease progression of an isolated strain.

RevDate: 2019-09-24

Lin Q, Sun H, Yao K, et al (2019)

The Prevalence, Antibiotic Resistance and Biofilm Formation of Staphylococcus aureus in Bulk Ready-To-Eat Foods.

Biomolecules, 9(10): pii:biom9100524.

The prevalence of Staphylococcus aureus in 2160 bulk ready-to-eat foods from the Sichuan province of China during 2013-2016 was investigated. The antibiotic resistance and the associated genes, as well as biofilm formation capacity of the S. aureus isolates were measured. Furthermore, the relationship between the antibiotic resistance and the resistant genes was discussed. It was found that 54 S. aureus isolates were recovered, and their prevalence in meat products, dairy, fruit and vegetables, and desserts were 31 (2.6%), six (3.0%), nine (2.2%) and eight (2.3%), respectively. Most strains (52/54) were resistant to at least one of the antibiotics, and 21 isolates were identified as multidrug-resistant (MDR) S. aureus. Three isolates were found to be methicillin-resistant S. aureus. Penicillin, erythromycin, clindamycin, tetracycline and inducible clindamycin resistance were determined as the predominant antibiotics, and the isolates with the phenotypic resistance on these five antibiotics were all determined positive for the resistant gene associated. In total, 33 of 54 S. aureus isolates showed biofilm formation capacity, including two strong biofilm producers, one moderate and 30 weak ones. Two S. aureus isolates with strong biofilm formation abilities showed multi-drug resistance, and one moderate biofilm producer was resistant to two categories of antibiotics.

RevDate: 2019-09-24

Ghimire N, Pettygrove BA, Pallister KB, et al (2019)

Direct Microscopic Observation of Human Neutrophil-Staphylococcus aureus Interaction In Vitro Suggests a Potential Mechanism for Initiation of Biofilm Infection on an Implanted Medical Device.

Infection and immunity pii:IAI.00745-19 [Epub ahead of print].

The ability of human neutrophils to clear newly attached Staphylococcus aureus bacteria from a serum-coated glass surface was examined in vitro using time-lapse confocal scanning laser microscopy. Quantitative image analysis was used to measure the temporal change in bacterial biomass, neutrophil motility, and fraction of the surface area policed by neutrophils. In control experiments in which the surface was inoculated with bacteria but no neutrophils were added, prolific bacterial growth was observed. Neutrophils were able to control bacterial growth but only consistently when the neutrophil:bacteria number ratio exceeded approximately one. When pre-attached bacteria were given a head start and allowed to grow for three hours prior to neutrophil addition, neutrophils were unable to maintain control of the nascent biofilm. In these head start experiments, aggregates of bacterial biofilm with areas of 50 μm2 or larger formed and the growth of such aggregates continued even when multiple neutrophils attacked a cluster. These results suggest a model for the initiation of a biofilm infection in which a delay in neutrophil recruitment to an abiotic surface allows surface-attached bacteria time to grow and form aggregates that become protected from neutrophil clearance. Results from a computational model of the neutrophil-biofilm surface contest supported this conceptual model and highlighted the stochastic nature of the interaction. Additionally, we observed that both neutrophil motility and clearance of bacteria were impaired when oxygen tension was reduced to 0% or 2% O2SIGNIFICANCE Bacteria or yeast that form biofilms on implanted medical devices such as artificial hip joints cause troublesome infections. These device-associated infections are persistent because biofilm-embedded microorganisms are protected from antibiotics and host defenses. Three decades of research in antimicrobial coatings and non-stick surfaces have not yet solved the biofilm infection problem. Here we show in a model system that neutrophils can effectively clear contaminating Staphylococcus aureus bacteria from an abiotic surface, but they must be delivered quickly and in sufficient numbers. If neutrophil recruitment is delayed, undiscovered bacteria grow and form aggregates that evade engulfment and killing by white blood cells. This work opens a pathway to preventing infections on implanted medical devices by transiently boosting innate immune defenses.

RevDate: 2019-09-24

Erdmann J, Thöming JG, Pohl S, et al (2019)

The Core Proteome of Biofilm-Grown Clinical Pseudomonas aeruginosa Isolates.

Cells, 8(10): pii:cells8101129.

Comparative genomics has greatly facilitated the identification of shared as well as unique features among individual cells or tissues, and thus offers the potential to find disease markers. While proteomics is recognized for its potential to generate quantitative maps of protein expression, comparative proteomics in bacteria has been largely restricted to the comparison of single cell lines or mutant strains. In this study, we used a data independent acquisition (DIA) technique, which enables global protein quantification of large sample cohorts, to record the proteome profiles of overall 27 whole genome sequenced and transcriptionally profiled clinical isolates of the opportunistic pathogen Pseudomonas aeruginosa. Analysis of the proteome profiles across the 27 clinical isolates grown under planktonic and biofilm growth conditions led to the identification of a core biofilm-associated protein profile. Furthermore, we found that protein-to-mRNA ratios between different P. aeruginosa strains are well correlated, indicating conserved patterns of post-transcriptional regulation. Uncovering core regulatory pathways, which drive biofilm formation and associated antibiotic tolerance in bacterial pathogens, promise to give clues to interactions between bacterial species and their environment and could provide useful targets for new clinical interventions to combat biofilm-associated infections.

RevDate: 2019-09-24

Zhang XY, Sun K, Abulimiti A, et al (2019)

Microfluidic System for Observation of Bacterial Culture and Effects on Biofilm Formation at Microscale.

Micromachines, 10(9): pii:mi10090606.

Biofilms exist in the natural world and applied to many industries. However, due to the variety of characteristics caused by their complex components, biofilms can also lead to membrane fouling and recurrent infections which pose threats to human health. So, to make the best use of their advantages and avoid their disadvantages, knowing the best time and methods for improving or preventing biofilm formation is important. In situ observation without fluorescence labeling in microscale and according to a time scale is useful to research biofilm and confine its formation. In this study, we developed a microfluidic system for real-time observation of bacteria culture and biofilms development at microscale. We cultured E. coli ATCC 25922 on a chip at continuous flow of the velocity, which could promote bacterial formation. Biofilms formation under the condition of adding amoxicillin at different times is also discussed. In addition, the mixed strains from sludge were also cultured on chip, and possible factors in biofilm formation are discussed. Our results show that a microfluidic device could culture microorganisms in continuous flow and accelerate them to adhere to the surface, thereby promoting biofilm formation. Overall, this platform is a useful tool in research on initial biofilm formation, which can contribute to preventing biofouling and infections.

RevDate: 2019-09-24

Kerekes EB, Vidács A, Takó M, et al (2019)

Anti-Biofilm Effect of Selected Essential Oils and Main Components on Mono- and Polymicrobic Bacterial Cultures.

Microorganisms, 7(9): pii:microorganisms7090345.

Biofilms are surface-associated microbial communities resistant to sanitizers and antimicrobials. Various interactions that can contribute to increased resistance occur between the populations in biofilms. These relationships are the focus of a range of studies dealing with biofilm-associated infections and food spoilage. The present study investigated the effects of cinnamon (Cinnamomum zeylanicum), marjoram (Origanum majorana), and thyme (Thymus vulgaris) essential oils (EOs) and their main components, i.e., trans-cinnamaldehyde, terpinen-4-ol, and thymol, respectively, on single- and dual-species biofilms of Escherichia coli, Listeria monocytogenes, Pseudomonas putida, and Staphylococcus aureus. In dual-species biofilms, L. monocytogenes was paired with each of the other three bacteria. Minimum inhibitory concentration (MIC) values for the individual bacteria ranged between 0.25 and 20 mg/mL, and trans-cinnamaldehyde and cinnamon showed the highest growth inhibitory effect. Single-species biofilms of L. monocytogenes, P. putida, and S. aureus were inhibited by the tested EOs and their components at sub-lethal concentrations. Scanning electron microscopy images showed that the three-dimensional structure of mature biofilms embedded in the exopolysaccharide matrix disappeared or was limited to micro-colonies with a simplified structure. In most dual-species biofilms, to eliminate living cells from the matrix, concentrations exceeding the MIC determined for individual bacteria were required.

RevDate: 2019-09-24

Das D, Bhattacharjee H, Gogoi K, et al (2019)

Intraocular lens biofilm formation supported by scanning electron microscopy imaging.

Indian journal of ophthalmology, 67(10):1708-1709.

RevDate: 2019-09-24

Eduok U, Ohaeri E, J Szpunar (2019)

Accelerated corrosion of pipeline steel in the presence of Desulfovibrio desulfuricans biofilm due to carbon source deprivation in CO2 saturated medium.

Materials science & engineering. C, Materials for biological applications, 105:110095.

The chemistry of bacterial biofilms as well as the nutritional composition of culture environments may differ at any time within a growth process, especially for SRB consortia within oil wells with limited carbon sources. In the oilfield, the presence of SRB biofilms on surfaces of steel substrates leads to microbiologically influenced corrosion and compromised material integrity. In this work, the survival of SRB cells and their impact on the pipeline steel corrosion within simulated CO2-saturated oilfield-produced water with different concentrations of organic carbon source have been investigated. Cell counts reduced with the level of carbon source reduction (CSR) after incubation but more sessile cells survived at 80% CSR (moderate carbon starvation) compared to 100% CSR (extreme carbon starvation). The energy needed for cellular survival as well as biological support toward MIC could have been harnessed by a combination of extracellular Feo oxidation and intracellular sulfate reduction even after carbon source starvation. Severe anodic steel dissolution was observed at the end of the culture period within the simulated CO2-saturated oilfield-produced water, and this is attributed to SRB-led MIC and CO2 corrosion. Pipeline steel corroded more when cultured within 80% CSR compared to the medium with both lactate and citrate. Steel substrate corroded less with 100% CSR due to severely weakened SRB biofilms from nutrient deprivation.

RevDate: 2019-09-23

Sales LS, Guimarães GN, Wijesinghe GK, et al (2019)

Addition of hydrogen peroxide to methylene blue conjugated to β-cyclodextrin in photodynamic antimicrobial chemotherapy in S. mutans biofilm.

Photodiagnosis and photodynamic therapy pii:S1572-1000(19)30224-8 [Epub ahead of print].

OBJECTIVE: This study evaluated the effect of hydrogen peroxide addition on β-cyclodextrin-conjugated methylene blue in photodynamic antimicrobial chemotherapy (PACT) inS. mutans biofilm model using laser or light emitting diode (LED) (λ = 660 nm).

METHODS: A preliminary assay was performed to evaluate the cytotoxicity of hydrogen peroxide in oral fibroblasts by the colorimetric method (MTT). Afterwards, groups were divided into (n = 3, in triplicate): C (negative control), CX - chlorhexidine 0.2% (positive control), P (methylene blue/β-cyclodextrin), H (Hydrogen Peroxide at 40 µM), PH, L (Laser), LP, LH (Laser+Hydrogen Peroxide), LPH, LED, LEDP, LEDH, and LEDPH. The biofilm was formed in 24 h with BHI + 1% sucrose (w/v). Light irradiations were conducted with laser, 9 J, 323 J/cm2, 113 s or with LED, 8.1 J, 8.1 J/cm2 for 90 s. Microbial reduction was evaluated by counting the viable microorganisms of the biofilm after the respective treatments, in a selective culture medium, and laser confocal microscopy evaluation.

RESULTS: LP, LH, LPH, LEDP, LEDH, and LEDPH groups statistically reduced the counts ofS. mutans compared with the C group and the log reductions were of 1.87, 1.94, 2.19, 0.91, 0.92, and 1.33, respectively; the addition of hydrogen peroxide did not potentiate the microbial reductions (LPH and LEDPH) compared with the LP and LEDP groups.

CONCLUSION: The association of hydrogen peroxide with the conjugated β-cyclodextrin nanoparticle as photosensitizer did not result in an enhanced effect of PACT; hydrogen peroxide behaved as a photosensitizer, since it reduced the number ofS. mutans when associated with laser light.

RevDate: 2019-09-23

Ram MK, Naveen Kumar BT, Poojary SR, et al (2019)

Evaluation of biofilm of Vibrio anguillarum for oral vaccination of Asian seabass, Lates calcarifer (BLOCH, 1790).

Fish & shellfish immunology pii:S1050-4648(19)30937-4 [Epub ahead of print].

The present study evaluated the biofilm (BF) of Vibrio anguillarum for oral vaccination of Asian seabass, Lates calcarifer. An 80-day experiment was carried out in circular fiber-reinforced plastic (FRP) tanks using free cell (FC) and BF of Vibrio anguillarum with triplicate in each. Heat-inactivated FC and BF cells at 107, 1010 and 1013 CFU/g fish/d were fed to fish for 20 days, agglutination antibody titer estimated at each 10 days interval up to 60-day post vaccination. As compared to FC and control there was a significant increase in agglutinating antibody titer in the biofilm vaccinated fishes. Among the 3 doses, BF at 1010 cfu/g fish/d was considered the ideal dose for vaccination. Relative percentage survival (RPS) was higher in biofilm vaccinated fish (85.4%) compared to that with free cells (27.0%). The study demonstrated the better performance of V. anguillarum biofilm oral vaccine compared that with free cell vaccine in L. calcarifer. The study further supports better performance of biofilm vaccine model with one more bacterial pathogen in a high carnivore fish.

RevDate: 2019-09-23

Campos-Silva R, Roberta BF, Silva TD, et al (2019)

Alternative method in Galleria mellonella larvae to study biofilm infection and treatment.

Microbial pathogenesis pii:S0882-4010(19)31143-X [Epub ahead of print].

In vivo studies are crucial decision-maker step in order to translate in vitro data to an applied therapy. Considering this we describe a simple method that analyzes and quantifies biofilm formation inside the Galleria mellonella larvae. Toothbrush bristles were employed as an abiotic surface to mimic a medical device. A standardized inoculum of Staphylococcus aureus was systemically injected in the larvae together with the insertion of a bristle in the last proleg pair. After incubation adhered cells were detached from bristles and quantified by colony-forming units (CFU) counting using staphylococci-selective medium. About 3 × 106 CFU of S. aureus were recovered from bristles and scanning electron microscopy images confirmed biofilm formation. Control group did not show adherent bacteria, as demonstrated by absence of CFU counting and SEM images, indicating that the insertion procedure is free of bacterial contamination. We present a feasible method to evaluate bacterial biofilm formation in vivo that in the near future can be used to evaluate antibiofilm compounds.

RevDate: 2019-09-23

De Carolis E, Soldini S, La Rosa M, et al (2019)

BIOF-HILO Assay: A New MALDI-TOF Mass Spectrometry Based Method for Discriminating Between High- and Low-Biofilm-Producing Candida parapsilosis Isolates.

Frontiers in microbiology, 10:2046.

Candida parapsilosis is the most frequent cause of catheter-related candidemia among non-Candida albicans species. This may be related to intrinsic capabilities as adhering and forming a biofilm on abiotic surfaces such as on medical devices. As previously demonstrated, patients infected with high biofilm-producing C. parapsilosis isolates had a greater mortality risk compared to patients infected with low biofilm-producing C. parapsilosis isolates. We developed the BIOF-HILO assay, a MALDI-TOF mass spectrometry (MS)-based assay, which compares mass spectra obtained from attached and suspended isolate cells during the early (i.e., 3-h) adhesion phase of in vitro biofilm formation. The composite correlation index (CCI) analysis was used to discriminate between mass spectra differences of the two cell types, classifying all 50 C. parapsilosis clinical isolates, included in the study, after only 3-h of testing, in high or low biofilm producers. All high (n = 25) or low (n = 25) biofilm producers had, according to CCI mass spectra comparison values, higher or lower than one CCI ratios, which were obtained by dividing the CCIsuspended cells by the CCIattached cells. In conclusion, the BIOF-HILO assay allows a rapid categorization of C. parapsilosis clinical isolates in high or low biofilm producers. This information, if timely provided to physicians, may improve treatment outcomes in patients with C. parapsilosis candidemia.

RevDate: 2019-09-23

Alviz-Gazitua P, Fuentes-Alburquenque S, Rojas LA, et al (2019)

Corrigendum: The Response of Cupriavidus metallidurans CH34 to Cadmium Involves Inhibition of the Initiation of Biofilm Formation, Decrease in Intracellular c-di-GMP Levels, and a Novel Metal Regulated Phosphodiesterase.

Frontiers in microbiology, 10:2014.

[This corrects the article DOI: 10.3389/fmicb.2019.01499.].

RevDate: 2019-09-23

Kitti T, Seng R, Thummeepak R, et al (2019)

Biofilm Formation of Methicillin-resistant Coagulase-Negative Staphylococci Isolated from Clinical Samples in Northern Thailand.

Journal of global infectious diseases, 11(3):112-117.

Background: Methicillin-resistant coagulase-negative staphylococci (MR-CoNS) are multidrug-resistant bacteria that are difficult to treat because of their ability to form biofilms.

Objectives: In the present study, we evaluated the antibiotic-resistant phenotypes, biofilm-forming ability, and biofilm associated genes of 55 clinical MR-CoNS isolates obtained from two hospitals in Thailand.

Materials and Methods: MALDI-TOF-MS and tuf gene sequencing were performed to determine the species of all isolates. Biofilm production was determined using Congo red agar (CRA) and the microtiter plate (MTP) assay. Biofilm-associated genes were characterized using polymerase chain reaction (PCR).

Results: Among the 55 MR-CoNS isolates, five species were identified as Staphylococcus haemolyticus (34.5%), Staphylococcus epidermidis (32.7%), Staphylococcus capitis (18.2%), Staphylococcus cohnii (9.1%), and Staphylococcus hominis (5.5%). The antimicrobial susceptibility pattern of MR-CoNS isolates indicated high resistance to cefoxitin (100%), penicillin (98.2%), erythromycin (96.4%), ciprofloxacin (67.3%), sulfamethoxazole/trimethoprim (67.3%), gentamicin (67.3%), and clindamycin (63.6%). All the isolates were susceptible to vancomycin and linezolid. The biofilm production was detected in 87.3% isolates through the CRA method and in 38.1% isolates through the MTP assay. The prevalence rates of icaAD, bap, fnbA, and cna were 18.2%, 12.7%, 47.3%, and 27.3%, respectively. There were significant differences in the presence of these biofilm-associated genes among the MR-CoNS isolates. Moreover, quantitative biofilm formation was significantly different among MR-CoNS species.

Conclusion: The present study revealed that biofilm-associated genes are important for biofilm biomass in MR-CoNS isolates, and the findings of this study are essential for finding new strategies to control biofilm formation and prevent the spread of MR-CoNS infectious diseases.

RevDate: 2019-09-22

Mitchell K, Lima AT, P Van Cappellen (2019)

Selenium in buoyant marine debris biofilm.

Marine pollution bulletin, 149:110562 pii:S0025-326X(19)30706-4 [Epub ahead of print].

Marine debris is widespread in all the world's oceans. Currently little is understood about how marine debris affects the chemistry of the surface oceans, particularly trace elements that can adsorb to the surface of marine debris, especially plastic debris, or be taken up by biofilms and algae growing on the surface of marine debris. Selenium (Se) is a micronutrient that is essential to all living organisms. Average seawater Se concentrations in the modern ocean are <1 nM. Here we measure the concentration of Se in surface water and one deep water sample and the concentration of Se found in algae/biofilms growing on the surface of macro-debris collected in October of 2012. Concentrations of Se in biofilm varied more according to the type of biofilm rather than the type of plastic. However, further Se measurements are needed for more conclusive results.

RevDate: 2019-09-22

Acevedo Alonso V, S Lackner (2019)

Membrane Aerated Biofilm Reactors - How longitudinal gradients influence nitrogen removal - A conceptual study.

Water research, 166:115060 pii:S0043-1354(19)30834-6 [Epub ahead of print].

Membrane-aerated biofilm reactors are becoming more important for nitrogen removal in the wastewater sector. One-dimensional (1D) models are widely used to study the performance of such systems; however, 1D models are not able to simulate the longitudinal gradients that exist in the reactor. Although there is experimental evidence that points to the existence of longitudinal gradients simple modeling approaches that consider these gradients are not yet developed. This study proposes a novel multi-compartment model that simulates the longitudinal substrate and oxygen gradients. It assesses the effects of temperature, biofilm thickness, number of compartments, and flow configuration (liquid and gas phase) on the modeling results. Additionally, it compares the capabilities of a traditional 1D model with those of the novel multi-compartment model. Our results show that a classical 1D model predicts a lower total dissolved nitrogen concentration (TDN) in the effluent in contrast to the predictions of the multi-compartment model. In the worst-case scenario, the TDN predicted by the traditional 1D model was three times lower than the prediction of the multi-compartment model. The results delivered by the models differ also in the axial gradients. The traditional 1D model, for example, predicted an oxygen concentration at the membrane surface of 0.4 mg-O2/l while the multi-compartment model predicted a concentration of 2.9 mg-O2/l. Finally, the results of this study show that the longitudinal oxygen gradient has an important effect on both, biomass distribution and effluent TDN, whereas the longitudinal substrate exclusively affected the effluent TDN.

RevDate: 2019-09-21

Amaechi BT, Abdul Azees PA, Menon S, et al (2019)

In vitro evaluation of the effects of Ultrasound Tongue Scraper on bacteria and biofilm formation.

Journal of investigative and clinical dentistry [Epub ahead of print].

AIM: Oral malodor is a common condition caused by some Gram-negative oral bacteria, among which are the 3 red complex bacteria (RCB). The present study investigated the effectiveness of the Ultrasound Tongue Scraper (UTS) to disrupt the structural morphology of the bacteria and their biofilm.

METHODS: While developing over 72 hours, multispecies biofilms of RCB (Porphromonas gingivalis, Tryponema denticola, Tannerella forsythia) were treated every 24 hours with 1.6-MHz ultrasound waves generated with UTS. An untreated group served as controls. Confocal laser scanning microscopy was used to determine the biofilm thickness, biomass and live : dead cell ratio at each time point (24, 48 and 72 hours). Biofilm morphology and bacteria ultrastructure were viewed using scanning/transmission electron microscopy, respectively. Data were analyzed using ANOVA and Tukey tests.

RESULTS: At each time point, the 3 variables were significantly lower in treated samples than the untreated. Significant biofilm disruption was observed in treated samples at each time period while the untreated had intact biofilm morphology. Cells in treated samples showed disrupted cell wall, cytoplasmic material, huge vacuoles and heterogeneity in electron density, while these cell organelles remained intact in untreated samples.

CONCLUSION: The UTS has an inhibitory effect on RCB and could be useful for oral malodor management.

RevDate: 2019-09-21

Li S, Wang Y, Li X, et al (2019)

Enhancing the Thermo-Stability and Anti-Biofilm Activity of Alginate Lyase by Immobilization on Low Molecular Weight Chitosan Nanoparticles.

International journal of molecular sciences, 20(18): pii:ijms20184565.

Bacterial biofilm causes severe antibiotic resistance. An extracellular polymeric substance (EPS) is the main component in the bacterial biofilm. Alginate is a key EPS component in the biofilm of Pseudomonas aeruginosa and responsible for surface adhesion and stabilization of biofilm. Alginate lyase has emerged as an efficient therapeutic strategy targeting to degrade the alginate in the biofilm of P. aeruginosa. However, the application of this enzyme is limited by its poor stability. In this study, chitosan nanoparticles (CS-NPs) were synthesized using low molecular weight chitosan and alginate lyase Aly08 was immobilized on low molecular weight chitosan nanoparticles (AL-LMW-CS-NPs). As a result, the immobilization significantly enhanced the thermal stability and reusability of Aly08. In addition, compared with free Aly08, the immobilized AL-LMW-CS-NPs exhibited higher efficiency in inhibiting biofilm formation and interrupting the established mature biofilm of P. aeruginosa, which could reduce its biomass and thickness confirmed by confocal microscopy. Moreover, the biofilm disruption greatly increased the antibiotic sensitivity of P. aeruginosa. This research will contribute to the further development of alginate lyase as an anti-biofilm agent.

RevDate: 2019-09-21

Wang X, Liu B, Pan X, et al (2019)

Transport and retention of biogenic selenium nanoparticles in biofilm-coated quartz sand porous media and consequence for elemental mercury immobilization.

The Science of the total environment, 692:1116-1124.

Bacterial biofilms are structured cell communities embedded in a matrix of extracellular polymeric substances (EPS) and a ubiquitous growth form of bacteria in the environment. A wide range of interactions between biofilms and nanoparticles have been reported. In the present study, the influence of a mixed bacterial biofilm on retention of biogenic selenium nanoparticles (BioSeNPs) and consequences for immobilization of elemental mercury (Hg0) in a porous quartz sand system were examined. BioSeNPs were significantly retained in the presence of a biofilm through electrical double layer effects, hydrogen bonding, and hydrophobic, steric and bridging interactions. Moreover, enhanced surface roughness, pore clogging, sieving and entrapment effects mediated by the biofilm also contributed to deposition of BioSeNPs. Whereas, thiol groups associated with the biofilm is a little helpful for the capture of Hg0. It is proposed that oxidative complexation between Hg0 and thiol compounds or S containing organic matter in the biofilm may result in the formation of Hg2+-thiolate complexes and HgS during the binding of Hg0 with BioSeNPs. The formation of mercury selenide was also involved in Hg0 immobilization in the porous quartz sand system.

RevDate: 2019-09-20

Cai X, Yao L, Sheng Q, et al (2019)

Influence of a biofilm bioreactor on water quality and microbial communities in a hypereutrophic urban river.

Environmental technology [Epub ahead of print].

Biofilms play an important role in degradation, transformation and assimilation of anthropogenic pollutants in aquatic ecosystems. In this study, we assembled a tubular bioreactor containing a biofilm substrate and aeration device, which was introduced into mesocosms to explore the effects of bioreactor on physicochemical and microbial characteristics of a hypereutrophic urban river. The biofilm bioreactor greatly improved water quality, especially by decreasing dissolved inorganic nitrogen (DIN) concentrations, suggesting that biofilms were the major sites of nitrification and denitrification with an oxygen concentration gradient. The biofilm bioreactor increased the abundance of planktonic bacteria, whereas diversity of the planktonic microbial community decreased. Sequencing revealed that Proteobacteria, Bacteroidetes, Planctomycetes, and Actinobacteria were the four predominant phyla in the planktonic microbial community, and the presence of the biofilm bioreactor increased the relative abundance of Proteobacteria. Variations in microbial communities were most strongly affected by the presence of the biofilm bioreactor, as indicated by principal component analysis (PCA) and redundancy analysis (RDA). This study provides valuable insights into changes in ecological characteristics associated with self-purification processes in hypereutrophic urban rivers, and and may be of important for the application of biofilm bioreactor in natural urban river.

RevDate: 2019-09-20

Bali EB, Türkmen KE, Erdönmez D, et al (2019)

Comparative Study of Inhibitory Potential of Dietary Phytochemicals Against Quorum Sensing Activity of and Biofilm Formation by Chromobacterium violaceum 12472, and Swimming and Swarming Behaviour of Pseudomonas aeruginosa PAO1.

Food technology and biotechnology, 57(2):212-221.

Quorum sensing (QS) and biofilm formation are important mechanisms related to antibiotic resistance of many pathogens. Alternative treatments are needed to prevent recurrent or chronic infections caused by multi-resistant pathogens. Therefore, the aim of this study is to investigate and compare the inhibitory potential of the dietary phytochemicals: curcumin, quercetin, apigenin, pyrogallol, gallic acid and luteolin against QS of and biofilm formation by Chromobacterium violaceum ATCC 12472 and the swimming and swarming abilities of Pseudomonas aeruginosa PAO1. Anti-QS potential of the phytochemicals was evaluated qualitatively and quantitatively using C. violaceum via the disk diffusion assay based on violacein pigment inhibition at the subminimal inhibitory concentrations ranging from 46.87 to 750 µg/mL. The results of anti-QS and antibiofilm activities on C. violaceum demonstrated that all the phytochemicals except pyrogallol and gallic acid inhibited violacein production (from (11.0±0.1) to (88.2±0.1) %) in a concentration-dependent manner. In addition, the biofilm formation was also significantly inhibited (p<0.05) in the presence of all the phytochemicals ((1.38±0.08)-(84.2±0.2) %). In the present study, the results revealed that quercetin, curcumin, apigenin and luteolin could be promising QS and biofilm inhibitory agents against the C. violaceum 12472 biosensor system. Our findings also suggest that all the phytochemicals, especially curcumin, quercetin and pyrogallol, might be anti-pathogenic agents against P. aeruginosa PAO1 infections due to the ability to control QS. However, more comprehensive studies at the molecular level, explaining their anti-QS mechanisms, need to be conducted to confirm these results and identify the genes involved.

RevDate: 2019-09-19

Abushahba F, Söderling E, Aalto-Setälä L, et al (2019)

Air-Abrasion with bioactive glass eradicates S. mutans biofilm from sandblasted and acid etched titanium surface.

The Journal of oral implantology [Epub ahead of print].

Streptococcus mutans is able to form a high-affinity biofilm on material surfaces. S. mutans has also been detected around infected implants. Bioactive glasses have been shown to possess antibacterial effects against S. mutans and other microorganisms. This in vitrostudy was performed to investigate the influence of bioactive glass air-abrasion on S. mutans biofilm on sandblasted and acid etched titanium surfaces. Sandblasted and acid etched commercially pure titanium discs were used as substrates for bacteria (n=107). The discs were immersed in an S. mutans solution and incubated for 21 h to form S. mutans biofilm. Twenty colonized discs were subjected to air-abrasion with the Bioglass®45S5 (45S5 BAG), experimental zinc oxide containing bioactive glass (Zn4 BAG) and inert glass. After the abrasion, the discs were incubated for 5 h in an anaerobic chamber followed by an assessment of viable S. mutans cells. Surface morphology was evaluation using SEM (n=12). Thrombogenicity of the glass particle abraded discs (n=75) was evaluated spectrophotometrically using whole blood clotting measurement at predetermined time points. Air-abrasion with 45S5 and Zn4 bioactive glass eradicated S. mutans biofilm. Significantly less viable S. mutans cells were found on discs abraded with the 45S5 or Zn4 BAGs compared to the inert glass (p<0.001). No significant differences were found in thrombogenicity since blood clotting was achieved for all substrates in min 40. Air-abrasion with BAG particles is effective in the eradication of S. mutans biofilm from sandblasted and acid etched titanium surfaces. Zn4 and 45S5 BAGs had similar biofilm eradicating effects but the Zn4 BAG could be more tissue-friendly. In addition, the steady release of zinc ions from the Zn4 may enhance the bone regeneration around the titanium implant and may thus have the potential to be used in the treatment of peri-implantitis. The use of either BAGs did not enhance the speed of blood coagulation.

RevDate: 2019-09-19

Mello DCR, de Oliveira JR, Cairo CAA, et al (2019)

Titanium alloys: in vitro biological analyzes on biofilm formation, biocompatibility, cell differentiation to induce bone formation, and immunological response.

Journal of materials science. Materials in medicine, 30(9):108 pii:10.1007/s10856-019-6310-2.

Biological effects of titanium (Ti) alloys were analyzed on biofilms of Candida albicans, Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus mutans, and Streptococcus sanguinis, as well as on osteoblast-like cells (MG63) and murine macrophages (RAW 264.7). Standard samples composed of aluminum and vanadium (Ti-6Al-4V), and sample containing niobium (Ti-35Nb) and zirconium (Ti-13Nb-13Zr) were analyzed. Monomicrobial biofilms were formed on the Ti alloys. MG63 cells were grown with the alloys and the biocompatibility (MTT), total protein (TP) level, alkaline phosphatase (ALP) activity, and mineralization nodules (MN) formation were verified. Levels of interleukins (IL-1β and IL-17), tumor necrosis factor alpha (TNF-α), and oxide nitric (NO) were checked, from RAW 264.7 cells supernatants. Data were statically analyzed by one-way analysis of variance (ANOVA) and Tukey's test, or T-test (P ≤ 0.05). Concerning the biofilm formation, Ti-13Nb-13Zr alloy showed the best inhibitory effect on E. faecalis, P. aeruginosa, and S. aureus. And, it also acted similarly to the Ti-6Al-4V alloy on C. albicans and Streptococcus spp. Both alloys were biocompatible and similar to the Ti-6Al-4V alloy. Additionally, Ti-13Nb-13Zr alloy was more effective for cell differentiation, as observed in the assays of ALP and MN. Regarding the stimulation for release of IL-1β and TNF-α, Ti-35Nb and Ti-13Nb-13Zr alloys inhibited similarly the synthesis of these molecules. However, both alloys stimulated the production of IL-17. Additionally, all Ti alloys showed the same effect for NO generation. Thus, Ti-13Nb-13Zr alloy was the most effective for inhibition of biofilm formation, cell differentiation, and stimulation for release of immune mediators.

RevDate: 2019-09-19

Oktay EA, Ersahan S, Sabuncuoglu FA, et al (2019)

Impact of various finishing and polishing techniques and composite materials on Candida albicans biofilm formation.

Medical mycology pii:5571552 [Epub ahead of print].

Candida albicans biofilms are commonly associated with severe oral infections. In dentistry, prosthetic and restorative materials are potential structures for the adhesion of C. albicans facilitating the formation of Candida biofilm and infection. Three composite resins (Charisma Classic, Sonic Fill, Estelite ∑ Quick) and two finishing-polishing systems (Biscover LV, Dental Finishing Disc) were evaluated for Candida biofilm formation. A Candida biofilm assay showed that both the resin and the finishing/polishing procedures affect Candida biofilm formation. Specifically, Candida biofilm formation was significantly lower in Sonic Fill resin than both Charisma Classic and Estelite ∑ Quick (P = .021). The type of finishing and polishing procedure also significantly affected the Candida biofilm formation to composite material (P < .001). Candida biofilm formation was more advanced after Biscover LV procedure than Dental Finishing Disc procedure.

RevDate: 2019-09-19

Craft KM, Nguyen JM, Berg LJ, et al (2019)

Methicillin-resistant Staphylococcus aureus (MRSA): antibiotic-resistance and the biofilm phenotype.

MedChemComm, 10(8):1231-1241 pii:c9md00044e.

Staphylococcus aureus (S. aureus) is an asymptomatic colonizer of 30% of all human beings. While generally benign, antibiotic resistance contributes to the success of S. aureus as a human pathogen. Resistance is rapidly evolved through a wide portfolio of mechanisms including horizontal gene transfer and chromosomal mutation. In addition to traditional resistance mechanisms, a special feature of S. aureus pathogenesis is its ability to survive on both biotic and abiotic surfaces in the biofilm state. Due to this characteristic, S. aureus is a leading cause of human infection. Methicillin-resistant S. aureus (MRSA) in particular has emerged as a widespread cause of both community- and hospital-acquired infections. Currently, MRSA is responsible for 10-fold more infections than all multi-drug resistant (MDR) Gram-negative pathogens combined. Recently, MRSA was classified by the World Health Organization (WHO) as one of twelve priority pathogens that threaten human health. In this targeted mini-review, we discuss MRSA biofilm production, the relationship of biofilm production to antibiotic resistance, and front-line techniques to defeat the biofilm-resistance system.

RevDate: 2019-09-19

Weng PL, Ramli R, RA Hamat (2019)

Antibiotic Susceptibility Patterns, Biofilm Formation and esp Gene among Clinical Enterococci: Is There Any Association?.

International journal of environmental research and public health, 16(18): pii:ijerph16183439.

Enterococci are commonly found in humans, animals and environments. Their highly adaptive mechanisms are related to several virulent determinants and their ability to resist antibiotics. Data on the relationship between the esp gene, biofilm formation and antibiotic susceptibility profiles may differ between countries. This cross-sectional study was conducted to determine the proportion of esp gene and biofilm formation among Enterococcus faecalis and Enterococcus faecium clinical isolates. We also investigated the possible association between the esp gene with antibiotic susceptibility patterns and biofilm formation. The isolates were collected from clinical samples and identified using biochemical tests and 16SRNA. Antibiotic susceptibility patterns and a biofilm assay were conducted according to the established guidelines. Molecular detection by PCR was used to identify the esp gene using established primers. In total, 52 and 28 of E. faecalis and E. faecium were identified, respectively. E. faecium exhibited higher resistance rates compared to E. faecalis as follows: piperacillin/tazobactam (100% versus 1.9%), ampicillin (92.8% versus 1.9%), high-level gentamicin resistance (HLGR) (89.3% versus 25.0%) and penicillin (82.1% versus 7.7%). E. faecium produced more biofilms than E. faecalis (59.3% versus 49.0%). E. faecium acquired the esp gene more frequently than E. faecalis (78.6% versus 46.2%). Interestingly, the associations between ampicillin and tazobactam/piperacillin resistance with the esp gene were statistically significant (X2 = 4.581, p = 0.027; and X2 = 6.276, p = 0.012, respectively). Our results demonstrate that E. faecium exhibits high rates of antimicrobial resistance, esp gene acquisition and biofilm formation. These peculiar traits of E. faecium may have implications for the management of enterococcal infections in hospitals. Thus, concerted efforts by all parties in establishing appropriate treatment and effective control measures are warranted in future.

RevDate: 2019-09-18

Preetham E, Rubeena AS, Vaseeharan B, et al (2019)

Anti-biofilm properties and immunological response of an immune molecule lectin isolated from shrimp Metapenaeus monoceros.

Fish & shellfish immunology pii:S1050-4648(19)30916-7 [Epub ahead of print].

The study is carried out to understand the antimicrobial and immunological response of a potential immune molecule lectin, MmLec isolated from haemolymph of Speckled shrimp, Metapenaeus monoceros. MmLec was purified using mannose coupled Sepharose CL-4B affinity chromatography, which was further subjected on SDS-PAGE to ascertain the distribution of their molecular weight. Sugar binding specificity assay was conducted at various pH and temperatures to investigate the binding affinity of MmLec towards the specific carbohydrate molecule. Functional analysis of immune molecule MmLec included haemagglutination assays performed using human erythrocytes and yeast agglutination activity against Saccharomyces cerevisiae which, were analyzed using light microscopy. In order to study the antimicrobial activity, two Gram-negative (Vibrio parahaemolyticus and Aeromonas hydrophila) and two Gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria were treated with purified MmLec. Moreover, these bacterial species were also treated at different concentration of the MmLec to speculate the antibiofilm properties of MmLec which was analyzed under Light Microscopy and Confocal Laser Scanning Microscopy. In addition, other functional characterization of MmLec showed the uniqueness of MmLec in agglutination of human erythrocyte as well as the cells of yeast Saccharomyces cerevisiae. Also, the phenoloxidase activity and encapsulation assay was evaluated. MTT assay displayed that MmLec are potent in anticancer activity. The study will help to understand the immunological interference and antimicrobial nature of MmLec which would be supportive in establishing a potential therapeutic tool and to develop better and novel disease control strategies in shrimp and farmed aquaculture industries as well as in health management.

RevDate: 2019-09-18

Vijayakumar K, T Ramanathan (2019)

Musa acuminata and its bioactive metabolite 5-Hydroxymethylfurfural mitigates quorum sensing (las and rhl) mediated biofilm and virulence production of nosocomial pathogen Pseudomonas aeruginosa in vitro.

Journal of ethnopharmacology pii:S0378-8741(19)31484-9 [Epub ahead of print].

Musa acuminata, a tropical plant belongs to the family Musaceae. The fruit peels of this plant have been well documented for their therapeutic value in Asia and Africa. It has also been previously reported for numerous biological applications such as antimicrobial, antioxidant, itching, psoriasis and anti-diarrheal activities. Moreover, M. acuminata peels have been well known for its anti-healing and antiseptic properties and most commonly used for healing wounds and heat burns in South Asian and African traditional medicines.

AIM OF THE STUDY: To evaluate the QS-mediated antibiofilm and antivirulence potential of M. acuminata, and its bioactive metabolites 5-Hydroxymethylfurfural (5HMF) against Pseudomonas aeruginosa.

MATERIALS AND METHODS: The M. acuminata peel methanol extract (MAM) was evaluated for its antibiofilm potential against P. aeruginosa with increasing concentration. Besides, biofilm related phenomenon's such as total biofilm proteins, microcolony formation exopolysaccharides (EPS) and cell surface hydrophobicity (CSH) productions were also examined to support the antibiofilm potential of MAM. Further, MAM was evaluated for its antivirulence efficacy against P. aeruginosa by assessing the protease, LasA protease, LasB elastase, pyocyanin, alginate and rhamnolipid productions at 400 μg ml-1 concentration. Transcriptional analysis of QS regulated virulence genes expression level was also done by real-time PCR analysis. Then, the MAM was subjected to column chromatography for further fractions and the bioactive compounds present in MAM were identified by gas chromatograph-mass spectrometry analysis. Further, the major compounds such as 5-hydroxymethylfurfural, vaccenic acid and pentanoic acid identified from active fraction of MAM were evaluated for their antibiofilm and antivirulence potential against P. aeruginosa.

RESULTS: MAM significantly inhibited the biofilm formation in P. aeruginosa at 400 μg ml-1 concentration which also inhibited the production of biofilm proteins, biofilm adherence, EPS and CSH productions to the level of 79%, 82% and 77% respectively. Further, the antivirulence potential was confirmed through numerous virulence inhibition assays. The MAM at 400 μg ml-1 concentration inhibited the QS-mediated virulence production such as protease, LasA protease, LasB elastase, pyocyanin, alginate and rhamnolipid productions to the level of 77%, 75%, 68%, 80%, 78% and 69% respectively. Moreover, the results of qPCR analysis confirmed the downregulation of QS regulated virulence genes expression upon treatment with MAM. The chromatographic analysis revealed the presence of 5-Hydroxymethylfurfural (5HMF), vaccenic acid and pentanoic acid in MAM and the potential bioactive compounds with antibiofilm and antivirulence was identified as 5-hydroxymethylfurfural, without exerting any growth inhibition in P. aeruginosa.

CONCLUSION: This study investigated the ideal antibiofilm and antivirulence potential of MAM and its bioactive compound 5HMF, and confirms the ethnopharmacological value of these peels against P. aeruginosa infections.

RevDate: 2019-09-18

She P, Wang Y, Liu Y, et al (2019)

Effects of exogenous glucose on Pseudomonas aeruginosa biofilm formation and antibiotic resistance.

MicrobiologyOpen [Epub ahead of print].

Pseudomonas aeruginosa is commonly found in nosocomial and life-threatening infections in patients. Biofilms formed by P. aeruginosa exhibit much greater resistance to antibiotics than the planktonic form of the bacteria. Few groups have studied the effects of glucose, a major carbon source, and metabolite, on P. aeruginosa biofilm formation and on its metabolic pathways. In this study, we investigated the effect of glucose on the biofilm formation ability of P. aeruginosa and carried out a metabolomic analysis to identify whether glucose alters the metabolic activity of P. aeruginosa in biofilms. We found that glucose efficiently promoted P. aeruginosa biofilm formation by upregulating the expression of the extracellular polysaccharide-related gene pslA. Treatment with glucose caused an increase in 7 metabolites (including 3-hydroxypropionic acid, glucose-6-phosphate, and 2,3-dimethylsuccinic acid) and a decrease in 18 metabolites (including myo-inositol, glutamine, and methoxamedrine) in the biofilm. In addition, there was a synergistic effect between glucose and horse serum on biofilm formation when the two were added in combination, which also increased the resistance of biofilm to levofloxacin therapy. Thus, our work sheds light on the underlying mechanisms by which glucose may enhance biofilm formation and identifies novel targets for developing strategies to counteract biofilm formation.

RevDate: 2019-09-18

Wang H, Palmer J, S Flint (2019)

Function of pYV Plasmid on Biofilm Formation of Yersinia enterocolitica ERL032123 in the Presence of Ca2.

Journal of food protection [Epub ahead of print].

The effect of the virulence plasmid pYV and calcium ions on biofilm of Yersinia enterocolitica biofilm formation was determined using a microtiter plate assay. Loss of the pYV plasmid prevented biofilm formation and the presence of Ca2+ enhanced biofilm formation in cultures containing the pYV plasmid. Scanning electron microscopy supported the result from the microtiter plate assay showing that in the presence of Ca2+, the wild-type Y. enterocolitica strain formed a strong biofilm on a polycarbonate surface. The results implied that Ca2+ promotes Y. enterocolitica biofilm formation through the function of the pYV plasmid.

RevDate: 2019-09-18

Baumeister TUH, Staudinger M, Wirgenings M, et al (2019)

Halogenated anilines as novel natural products from a marine biofilm forming microalga.

Chemical communications (Cambridge, England) [Epub ahead of print].

The toxic halogenated anilines 2,4,6-tribromoaniline, 2,4,6-trichloroaniline and their dibromochloro and bromodichloro derivatives were considered as compounds of exclusive synthetic origin. Labeling studies and kinetic experiments confirmed that these substances are also biosynthesized by a marine biofilm forming microalga. They represent a novel class of halogenated natural products.

RevDate: 2019-09-18

Hwang G, Paula AJ, Hunter EE, et al (2019)

Catalytic antimicrobial robots for biofilm eradication.

Science robotics, 4(29):.

Magnetically driven robots can perform complex functions in biological settings with minimal destruction. However, robots designed to damage deleterious biostructures could also have important impact. In particular, there is an urgent need for new strategies to eradicate bacterial biofilms as we approach a post-antibiotic era. Biofilms are intractable and firmly attached structures ubiquitously associated with drug-resistant infections and destruction of surfaces. Existing treatments are inadequate to both kill and remove bacteria leading to reinfection. Here we design catalytic antimicrobial robots (CARs) that precisely and controllably kill, degrade and remove biofilms with remarkable efficiency. CARs exploit iron oxide nanoparticles (NPs) with dual catalytic-magnetic functionality that (i) generate bactericidal free radicals, (ii) breakdown the biofilm exopolysaccharide (EPS) matrix, and (iii) remove the fragmented biofilm debris via magnetic field driven robotic assemblies. We develop two distinct CAR platforms. The first platform, the biohybrid CAR, is formed from NPs and biofilm degradation products. After catalytic bacterial killing and EPS disruption, magnetic field gradients assemble NPs and the biodegraded products into a plow-like superstructure. When driven with an external magnetic field, the biohybrid CAR completely removes biomass in a controlled manner, preventing biofilm regrowth. Biohybrid CARs can be swept over broad swathes of surface or can be moved over well-defined paths for localized removal with microscale precision. The second platform, the 3D molded CAR, is a polymeric soft robot with embedded catalytic-magnetic NPs, formed in a customized 3D printed mold to perform specific tasks in enclosed domains. Vane-shaped CARs remove biofilms from curved walls of cylindrical tubes, and helicoid-shaped CARs drill through biofilm clogs, while simultaneously killing bacteria. In addition, we demonstrate applications of CARs to target highly confined anatomical surfaces in the interior of human teeth. These 'kill-degrade-and-remove' CARs systems could have significant impact in fighting persistent biofilm-infections and in mitigating biofouling of medical devices and diverse surfaces.

RevDate: 2019-09-18

Veloz JJ, Alvear M, LA Salazar (2019)

Evaluation of Alternative Methods to Assess the Biological Properties of Propolis on Metabolic Activity and Biofilm Formation in Streptococcus mutans.

Evidence-based complementary and alternative medicine : eCAM, 2019:1524195.

Several biological activities have been reported for the Chilean propolis, among their antimicrobial and antibiofilm properties, due to its high polyphenol content. In this study, we evaluate alternative methods to assess the effect of Chilean propolis on biofilm formation and metabolic activity of Streptococcus mutans (S. mutans), a major cariogenic agent in oral cavity. Biofilm formation was studied by using crystal violet and by confocal microscopy. The metabolic activity of biofilm was evaluated by MTT and by flow cytometry analysis. The results show that propolis reduces biofilm formation and biofilm metabolic activity in S. mutans. When the variability of the methods to measure biofilm formation was compared, the coefficient of variation (CV) fluctuated between 12.8 and 23.1% when using crystal violet methodology. On the other hand, the CV ranged between 2.2 and 3.3% with confocal microscopy analysis. The CV for biofilm's metabolic activity measured by MTT methodology ranged between 5.0 and 11.6%, in comparison with 1.9 to 3.2% when flow cytometry analysis was used. Besides, it is possible to conclude that the methods based on colored compounds presented lower precision to study the effect of propolis on biofilm properties. Therefore, we recommend the use of flow cytometry and confocal microscopy in S. mutans biofilm analysis.

RevDate: 2019-09-18

Marbach H, Mayer K, Vogl C, et al (2019)

Within-host evolution of bovine Staphylococcus aureus selects for a SigB-deficient pathotype characterized by reduced virulence but enhanced proteolytic activity and biofilm formation.

Scientific reports, 9(1):13479 pii:10.1038/s41598-019-49981-6.

Staphylococcus aureus is a major cause of bovine mastitis, commonly leading to long-lasting, persistent and recurrent infections. Thereby, S. aureus constantly refines and permanently adapts to the bovine udder environment. In this work, we followed S. aureus within-host adaptation over the course of three months in a naturally infected dairy cattle with chronic, subclinical mastitis. Whole genome sequence analysis revealed a complete replacement of the initial predominant variant by another isogenic variant. We report for the first time within-host evolution towards a sigma factor SigB-deficient pathotype in S. aureus bovine mastitis, associated with a single nucleotide polymorphism in rsbU (G368A → G122D), a contributor to SigB-functionality. The emerged SigB-deficient pathotype exhibits a substantial shift to new phenotypic traits comprising strong proteolytic activity and poly-N-acetylglucosamine (PNAG)-based biofilm production. This possibly unlocks new nutritional resources and promotes immune evasion, presumably facilitating extracellular persistence within the host. Moreover, we observed an adaptation towards attenuated virulence using a mouse infection model. This study extends the role of sigma factor SigB in S. aureus pathogenesis, so far described to be required for intracellular persistence during chronic infections. Our findings suggest that S. aureus SigB-deficiency is an alternative mechanism for persistence and underpin the clinical relevance of staphylococcal SigB-deficient variants which are consistently isolated during human chronic infections.

RevDate: 2019-09-18

Bjarnsholt T, Østrup Jensen P, M Alhede (2019)

Revival of Krebs-Ringer balanced salt solution for the investigation of polymorphonuclear leukocytes and Pseudomonas aeruginosa biofilm interaction.

Pathogens and disease pii:5570584 [Epub ahead of print].

To study the interaction between aggregating bacteria and polymorphonuclear leukocytes (PMNs) in vitro the chosen medium must favor both the isolated PMNs and the bacteria. To investigate the best-suited medium for the in vitro survival of isolated unactivated human PMNs, we compared three different mammalian cell media: Krebs-Ringer balanced salt solution (BSS), Hanks' BSS (HBSS) and Roswell Park Memorial Institute (RPMI) 1640. The death of PMNs was estimated as the release of lactate dehydrogenase activity. Furthermore, two types of serum, human (HS) and fetal bovine (FBS), were compared at different concentrations (0%, 2%, 5%, 10%) and at three different time points (2, 4, 20 h). We show that Krebs-Ringer BSS prolonged the survival of PMNs compared to HBSS and RPMI1640 and that the addition of 10% FBS significantly enhanced long-term survival (20 h) compared to HS. Furthermore, we observed aggregation of Pseudomonas aeruginosa when grown in the presence of either a mixture of histones, histone H3, arginine or lysine. In this study, we show that the use of Krebs-Ringer BSS is highly relevant for the study of the interaction of bacteria and PMNs in relation to novel treatment strategies of biofilm infections due to the reproduction of bacterial aggregation as seen in chronic bacterial infections.

RevDate: 2019-09-18

Song YG, SH Lee (2019)

Efficacy of newly developed denture cleaning device on physical properties of denture material and Candida biofilm.

Journal of dental sciences, 14(3):248-254.

Background/purpose: Electrolyzed water has antimicrobial activity against oral microbes. The purpose of this study was to investigate the effects of a denture cleaning device that uses electrolyzed water on Candida biofilm on denture base-material and the physical properties of the denture material.

Materials and methods: Denture base-resin disks were prepared with Polymethyl methacrylate. After the formation of Candida albicans biofilm on the resin disks, the antimicrobial activity of the denture cleaning device and the chemical cleanser against C. albicans biofilm was compared. The resin disks were also treated with the cleaning device and the chemical cleanser for 150 days, and the physical properties were analyzed by an atomic force microscope, Vickers hardness tester, and colorimeter.

Results: The denture cleaning device and the chemical cleanser reduced the levels of C. albicans biofilm on the denture resin. Upon immersing of the resin disks for 150 days, the electrolyzed water of the denture cleaning device did not significantly change the surface roughness of the specimens, but significantly reduced its Vickers hardness compared to the initial value. The color changes of the resin disk were 0.477 ± 0.076, 0.612 ± 0.095 and 0.562 ± 0.096 after treating with tap water, the chemical cleanser, and the denture cleaning device, respectively.

Conclusion: The denture cleaning device may be suitable for use by the elderly to clean dentures without side effects caused by the misuse of chemical cleanser.

RevDate: 2019-09-18

Thieme L, Hartung A, Tramm K, et al (2019)

MBEC Versus MBIC: the Lack of Differentiation between Biofilm Reducing and Inhibitory Effects as a Current Problem in Biofilm Methodology.

Biological procedures online, 21:18 pii:106.

Background: Biofilms are communities of aggregated, matrix-embedded microbial cells showing a high tolerance to an in principle adequate antibiotic therapy, often resulting in treatment failure. A major challenge in the management of biofilm-associated infections is the development of adequate, standardized biofilm susceptibility testing assays that are clinically meaningful, i.e. that their results correlate with treatment outcome. Different biofilm susceptibility endpoint parameters like the minimal biofilm eradication concentration (MBEC) or the minimal biofilm inhibitory concentration (MBIC) have been suggested as a guide for treatment of biofilm-associated infections, however with inconsistent perception and use among biofilm researchers, leading to confusion and contradictions among different anti-biofilm component studies and clinical trials.

Findings: Evaluation of anti-biofilm effects is mostly based on the untreated reference growth control biofilm measured at the same endpoint as the treated biofilm, neglecting the possible change of the untreated reference biofilm from the time point of pre-antimicrobial exposure to the measured endpoint. In this commentary, we point out the importance of individual quantification of mature, established biofilms before antimicrobial treatment for each biofilm model in order to draw conclusions on the measured biofilm effect size, i.e. biofilm reducing (MBEC) or biofilm inhibitory (MBIC) effects.

Conclusion: The assessment of pre-treatment biofilms contributes to a standardized use of biofilm susceptibility endpoint parameters, which is urgently needed to improve the clinical validity of future anti-biofilm assays.

RevDate: 2019-09-18

Sultan AR, Hoppenbrouwers T, Lemmens-den Toom NA, et al (2019)

During the Early Stages of Staphylococcus aureus Biofilm Formation, induced Neutrophil Extracellular Traps (NETs) are degraded by Autologous Thermonuclease.

Infection and immunity pii:IAI.00605-19 [Epub ahead of print].

Staphylococcus aureus extracellular DNA (eDNA) plays a crucial role in the structural stability of biofilms during bacterial colonization, on the contrary, host immune responses can be induced by bacterial eDNA. Previously we observed production of S. aureus thermonuclease during the early stages of biofilm formation in a mammalian cell culture medium. Using a fluorescence resonance energy transfer (FRET)-based assay, we detected thermonuclease activity of S. aureus biofilms grown in Iscove's modified Dulbecco's medium (IMDM) earlier compared to widely-studied tryptic soy broth (TSB) grown biofilms. The thermonuclease found was Nuc1, confirmed by mass spectrometry and competitive Luminex assay. These results indicate that biofilm development in IMDM may not rely on eDNA for structural stability. A bacterial viability assay in combination with wheat germ agglutinin (WGA) staining confirmed the accumulation of dead cells and eDNA in biofilms grown in TSB. However, in IMDM-grown biofilms minimal amounts of eDNA were found and instead, polysaccharide intercellular adhesin (PIA) was detected. To investigate if this early production of thermonuclease plays a role in immune modulation by biofilm, we studied the effect of thermonuclease on human neutrophil extracellular traps (NETs) formation using a nuc knockout and complemented strain. We confirmed that thermonuclease produced by early stages biofilms grown in IMDM degraded biofilm-induced NETs. Additionally, neither the presence of biofilms nor thermonuclease stimulated an increase in reactive oxygen species (ROS) production by neutrophils. Our findings indicated that S. aureus, during the early stages of biofilm formation, actively evades the host immune responses by producing thermonuclease.

RevDate: 2019-09-18

Wang ZH, Liu JM, Li CY, et al (2019)

Bacterial Biofilm Bioinspired Persistent Luminescence Nanoparticles with Gut-Oriented Drug Delivery for Colorectal Cancer Imaging and Chemotherapy.

ACS applied materials & interfaces [Epub ahead of print].

Colorectal cancer (CRC) now comes to be one of the leading causes of cancer incidence and mortality. Although nanomaterial-based drug delivery has been used for the treatment of colorectal cancer, inferior targeting ability of existing nanocarriers leads to inefficient treatment and side effects. Moreover, the majority of intravenously administered nanomaterials aggregate into the reticuloendothelial system, leaving certain hidden risk to human health. All those problems gave great demands for further construction of well-performed and biocompatible nanomaterials for in vivo theranostics. In the present work, from a biomimetic point of view, Lactobacillus reuteri biofilm (LRM) was coated on the surface of trackable zinc gallogermanate (ZGGO) near-infrared persistent luminescence mesoporous silica to create the bacteria bioinspired nanoparticles (ZGGO@SiO2@LRM), which hold the inherit capability of withstanding the digestion of gastric acid and targeted release 5-FU to colorectum. Through the background-free persistent luminescence bioimaging of ZGGO, the coating of LRM facilitated the localization of ZGGO@SiO2@LRM to the tumor area of colorectum for more than 24 h after intragastric administration. Furthermore, ZGGO@SiO2@LRM hardly entered the blood, which avoided possible damage to immune organs such as liver and spleen. In vivo chemotherapy experiment clearly demonstrated the number of tumors per mouse in ZGGO@SiO2@LRM group decreased by one-half compared with the 5-FU group (P < 0.001). To sum up, this LRM bioinspired nanoparticles could tolerate the digestion of gastric acid, aviod aggregation by the immune system, favor gut-oriented drug delivery, and targeted release oral 5-FU into colorectum for more than 24 h, which may give new application prospects for targeted delivery of oral drugs into the colorectum.

RevDate: 2019-09-16

Brown JL, Johnston W, Delaney C, et al (2019)

Polymicrobial oral biofilm models: simplifying the complex.

Journal of medical microbiology [Epub ahead of print].

Over the past century, numerous studies have used oral biofilm models to investigate growth kinetics, biofilm formation, structure and composition, antimicrobial susceptibility and host-pathogen interactions. In vivo animal models provide useful models of some oral diseases; however, these are expensive and carry vast ethical implications. Oral biofilms grown or maintained in vitro offer a useful platform for certain studies and have the advantages of being inexpensive to establish and easy to reproduce and manipulate. In addition, a wide range of variables can be monitored and adjusted to mimic the dynamic environmental changes at different sites in the oral cavity, such as pH, temperature, salivary and gingival crevicular fluid flow rates, or microbial composition. This review provides a detailed insight for early-career oral science researchers into how the biofilm models used in oral research have progressed and improved over the years, their advantages and disadvantages, and how such systems have contributed to our current understanding of oral disease pathogenesis and aetiology.

RevDate: 2019-09-16

Pelyuntha W, Chaiyasut C, Kantachote D, et al (2019)

Cell-free supernatants from cultures of lactic acid bacteria isolated from fermented grape as biocontrol against Salmonella Typhi and Salmonella Typhimurium virulence via autoinducer-2 and biofilm interference.

PeerJ, 7:e7555 pii:7555.

Background: Salmonella Typhi and Salmonella Typhimurium are the causative pathogens of salmonellosis, and they are mostly found in animal source foods (ASF). The inappropriate use of antibiotics enhances the possibility for the emergence of antibiotic resistance in pathogens and antibiotic residue in ASF. One promising alternative to antibiotics in animal farming is the use of lactic acid bacteria (LAB).

Methods: The present study was carried out the cells and/or the cell-free culture supernatants (CFCS) from beneficial LAB against S. Typhi and S. Typhimurium. The antibacterial mechanisms of LAB-CFCS as biocontrol agents against both Salmonella serovars were investigated through the analysis of anti-salmonella growth activity, biofilm inhibition and quorum quenching activity.

Results: Among 146 LAB strains isolated from 110 fermented food samples, the 2 strong inhibitory effect strains (WM33 and WM36) from fermented grapes against both Salmonella serovars were selected. Out of the selected strains, WM36 was the most effective inhibitor, which indicated S. Typhi by showing 95.68% biofilm inhibition at 20% biofilm inhibition concentration (BIC) and reduced 99.84% of AI-2 signaling interference. The WM33 was the best to control S. Typhimurium by producing 66.46% biofilm inhibition at only 15% BIC and 99.99% AI-2 signaling a reduction. The 16S rDNA was amplified by a polymerase chain reaction (PCR). The selected isolates were identified as Weissella viridescens WM33 and Weissella confusa WM36 based on nucleotide homology and phylogenetic analysis.

Conclusion: The metabolic extracts from Weissella spp. inhibit Salmonella serovars with the potential to be used as biocontrol agents to improve microbiological safety in the production of ASF.

RevDate: 2019-09-16

Saidi N, Owlia P, Marashi SMA, et al (2019)

Inhibitory effect of probiotic yeast Saccharomyces cerevisiae on biofilm formation and expression of α-hemolysin and enterotoxin A genes of Staphylococcus aureus.

Iranian journal of microbiology, 11(3):246-254.

Background and Objectives: Staphylococcus aureus, as an opportunistic pathogen, is the cause of a variety of diseases from mild skin infections to severe invasive infections and food poisoning. Increasing antibiotic resistance in S. aureus isolates has become a major threat to public health. The use of compounds produced by probiotics can be a solution to this problem. Thus, the purpose of this study was to investigate the effect of Saccharomyces cerevisiae on some virulence factors (biofilm, α-hemolysin, and enterotoxin A) of S. aureus.

Materials and Methods: Supernatant and lysate extracts were prepared from S. cerevisiae S3 culture. Sub-MIC concentrations of both extracts were separately applied to S. aureus ATCC 29213 (methicillin-sensitive S. aureus; MSSA) and S. aureus ATCC 33591 (methicillin-resistant S. aureus; MRSA) strains. Biofilm formation of these strains was measured by microtiter plate assay and expression level of α-hemolysin and enterotoxin A genes (hla and sea, respectively) using real-time PCR technique.

Results: The supernatant extract has reduced both biofilm formation and expression of sea and hla genes, while lysate extract had only anti-biofilm effects. The MRSA strain showed more susceptibility to yeast extracts than MSSA strain in all tests.

Conclusion: The present study exhibited favorable antagonistic effects of S. cerevisiae S3, as a probiotic yeast, on MSSA and MRSA strains. Based on the findings of this study, the compounds produced by this yeast can be used to control S. aureus infections; however, further similar studies should be conducted to confirm the findings of the present study.

RevDate: 2019-09-16

Liu J, Cai M, Yan H, et al (2019)

Yunnan Baiyao reduces hospital-acquired pressure ulcers via suppressing virulence gene expression and biofilm formation of Staphylococcus aureus.

International journal of medical sciences, 16(8):1078-1088 pii:ijmsv16p1078.

Yunnan Baiyao (YB) as a kind of famous Chinese herbal medicine, possessed hemostatic, invigorating the circulation of blood, and anti-inflammatory effects. Identifying strategies to protect patients at risk for hospital-acquired pressure ulcers (HAPU) is essential. Herein, our results showed that YB treatment can effectively reduce the acne wound area and improve efficacy in a comparative study of 60 cases HAPU patients with S. aureus positive of acne wound pathogens. Furthermore, YB inhibited HIa expression and suppressed accessory gene regulator (agr) system controlled by regulatory RNA II and RNA III molecule using pALC1740, pALC1742 and pALC1743 S. aureus strain linked to gfpuvr reporter gene. Moreover, YB downregulated cao mRNA expression and inhibited coagulase activity by RT-PCR, slide and tube coagulase test. Additionally, YB downregulated seb, sec, sed, and tsst-1 mRNA expression to suppress enterotoxin and tsst-1 secretion and adhesion function related genes sarA, icaA, and cidA mRNA expression. Taken together, the data suggest that YB may reduce HAPU via suppressing virulence gene expression and biofilm formation of S. aureus.

RevDate: 2019-09-15

Alfa MJ, H Singh (2019)

Impact of wet storage and other factors on biofilm formation and contamination of patient-ready endoscopes: a narrative review.

Gastrointestinal endoscopy pii:S0016-5107(19)32219-9 [Epub ahead of print].

The 2019 Food and Drug Administration report indicates that the clinical studies undertaken by the 3 main GI endoscope manufacturers demonstrate 5.4% of patient-ready duodenoscopes remain culture positive for high-concern organisms. The root causes of this persistent contamination are poorly understood. The objectives of this review include summarizing (1) the impact of inadequate manual cleaning, and inadequate drying during storage on the formation of build-up biofilm in endoscope channels, (2) the impact of de-foaming agents used during patient procedures on drying efficacy, (3) the data showing the importance of build-up biofilm on persistent microbial survival, and (4) potential impact of implementation of a Quality Systems approach in GI endoscopy reprocessing.

RevDate: 2019-09-15

Horiuchi A, Kokubu E, Warita T, et al (2019)

Synergistic biofilm formation by Parvimonas micra and Fusobacterium nucleatum.

Anaerobe pii:S1075-9964(19)30166-0 [Epub ahead of print].

Parvimonas micra is frequently isolated from lesions of apical periodontitis and is a major disease-related pathogen. One of the main causes of apical periodontitis is extraradicular biofilm. In this study, we investigated polymicrobial biofilm formation by P. micra and species associated with apical periodontitis. The coaggregation activity of P. micra with partner strains was investigated by visual assays. Synergistic biofilm formation was evaluated by cocultures of P. micra and partner strains. Growth of planktonic cells was measured by evaluating the absorbance at OD660, and biofilm formation was examined by staining with crystal violet. The effects of soluble components on synergistic biofilm formation and planktonic cell growth were examined after coculture of P. micra and other strains separated with a 0.4-μm pore-size porous membrane. P. micra coaggregated with Fusobacterium nucleatum, Porphyromonas gingivalis, or Capnoctyophaga ochracea. P. micra showed no coaggregation with Staphylococcus aureus, S. epidermidis, or Prevotella intermedia. In mixed cultures, biofilm formation by P. micra and F. nucleatum was greater than that by P. micra and P. gingivalis or C. ochracea. In separated cocultures, planktonic cell growth of P. micra was enhanced by each of the three species. Biofilm formation by P. micra was enhanced by F. nucleatum and C. ochracea; however, no significant enhancement was observed with P. gingivalis. These data indicated that P. micra and F. nucleatum had synergistic effects in biofilm formation and that these effects may be important for colonization by these two species in apical periodontitis lesions.

RevDate: 2019-09-14

Cheng H, Cheng D, Mao J, et al (2019)

Identification and characterization of core sludge and biofilm microbiota in anaerobic membrane bioreactors.

Environment international, 133(Pt A):105165 pii:S0160-4120(19)31610-1 [Epub ahead of print].

An analysis of sludge (i.e., 63 samples) and biofilm (i.e., 79 samples) sampled from 13 anaerobic membrane bioreactors (AnMBR) was conducted. Predominant microbial community identification and multivariate analysis indicate that these reactors showed different microbial community structure, but these differences had no impact on the overall AnMBR performance. Instead, core microbial genera which occurred in ≥90% of sludge (20 genera) and biofilm (12 genera) samples could potentially account for the AnMBR performance. A further calculation on net growth rate (NGR) of core genera in sludge suggested distribution into two main groups (i.e., I: low relative abundance and NGR, II: high relative abundance or high NGR). Consistent positive correlations between bacterial genera were observed among those that exhibited either high relative abundance or high NGR. The anaerobic microbial consortium in both sludge and biofilm were largely affected by stochastic dispersal and migration processes (i.e., neutral assembly). However, Acinetobacter spp. and Methanobacterium spp. occurred consistently in higher frequency in the biofilm but in lower occurrence frequency in the AnMBR permeate. Findings from this study suggest first, specific core microorganisms exist in the sludge regardless of the operating conditions of the AnMBRs, and second, prevention of biofoulant layer on anaerobic membranes can be devised by minimizing attachment of microbes on surfaces in a non-selective manner.

RevDate: 2019-09-14

Yuan Z, Tao B, He Y, et al (2019)

Remote eradication of biofilm on titanium implant via near-infrared light triggered photothermal/photodynamic therapy strategy.

Biomaterials, 223:119479 pii:S0142-9612(19)30578-2 [Epub ahead of print].

Biofilm formation is a main challenge in treatment of bone-implant-associated infections, resulting in tolerance to immune system and antibiotics. However, smart non-surgical or non-invasive treatment methods of combating established biofilm on an implant have been less reported. Herein, a therapeutic system consisting of mesoporous polydopamine nanoparticles (MPDA) to combat biofilm is reported for the first time. We develop a synergistic photothermal/photodynamic therapy (PTT/PDT) strategy aiming for biofilms eradication on titanium (Ti) implant, which is integrated with MPDA loading with photosensitizer Indocyanine Green (ICG) by π-π stacking. Specifically, MPDA is functionalized with RGD peptide to endow the modified Ti sample (Ti-M/I/RGD) with good cytocompatibility. More importantly, Ti-M/I/RGD implant remarkably kills Staphylococcus aureus (S. aureus) biofilm with an efficiency of 95.4% in vivo upon near infrared (NIR). After biofilm eradication, implant still displays great performance regarding osteogenesis and osseointegration. Overall, this study provides a PTT/PDT strtategy for the development of antibacterial Ti implants for potential orthpediac application.


RJR Experience and Expertise


Robbins holds BS, MS, and PhD degrees in the life sciences. He served as a tenured faculty member in the Zoology and Biological Science departments at Michigan State University. He is currently exploring the intersection between genomics, microbial ecology, and biodiversity — an area that promises to transform our understanding of the biosphere.


Robbins has extensive experience in college-level education: At MSU he taught introductory biology, genetics, and population genetics. At JHU, he was an instructor for a special course on biological database design. At FHCRC, he team-taught a graduate-level course on the history of genetics. At Bellevue College he taught medical informatics.


Robbins has been involved in science administration at both the federal and the institutional levels. At NSF he was a program officer for database activities in the life sciences, at DOE he was a program officer for information infrastructure in the human genome project. At the Fred Hutchinson Cancer Research Center, he served as a vice president for fifteen years.


Robbins has been involved with information technology since writing his first Fortran program as a college student. At NSF he was the first program officer for database activities in the life sciences. At JHU he held an appointment in the CS department and served as director of the informatics core for the Genome Data Base. At the FHCRC he was VP for Information Technology.


While still at Michigan State, Robbins started his first publishing venture, founding a small company that addressed the short-run publishing needs of instructors in very large undergraduate classes. For more than 20 years, Robbins has been operating The Electronic Scholarly Publishing Project, a web site dedicated to the digital publishing of critical works in science, especially classical genetics.


Robbins is well-known for his speaking abilities and is often called upon to provide keynote or plenary addresses at international meetings. For example, in July, 2012, he gave a well-received keynote address at the Global Biodiversity Informatics Congress, sponsored by GBIF and held in Copenhagen. The slides from that talk can be seen HERE.


Robbins is a skilled meeting facilitator. He prefers a participatory approach, with part of the meeting involving dynamic breakout groups, created by the participants in real time: (1) individuals propose breakout groups; (2) everyone signs up for one (or more) groups; (3) the groups with the most interested parties then meet, with reports from each group presented and discussed in a subsequent plenary session.


Robbins has been engaged with photography and design since the 1960s, when he worked for a professional photography laboratory. He now prefers digital photography and tools for their precision and reproducibility. He designed his first web site more than 20 years ago and he personally designed and implemented this web site. He engages in graphic design as a hobby.

Order from Amazon

This is a must read book for anyone with an interest in invasion biology. The full title of the book lays out the author's premise — The New Wild: Why Invasive Species Will Be Nature's Salvation. Not only is species movement not bad for ecosystems, it is the way that ecosystems respond to perturbation — it is the way ecosystems heal. Even if you are one of those who is absolutely convinced that invasive species are actually "a blight, pollution, an epidemic, or a cancer on nature", you should read this book to clarify your own thinking. True scientific understanding never comes from just interacting with those with whom you already agree. R. Robbins

963 Red Tail Lane
Bellingham, WA 98226


E-mail: RJR8222@gmail.com

Collection of publications by R J Robbins

Reprints and preprints of publications, slide presentations, instructional materials, and data compilations written or prepared by Robert Robbins. Most papers deal with computational biology, genome informatics, using information technology to support biomedical research, and related matters.

Research Gate page for R J Robbins

ResearchGate is a social networking site for scientists and researchers to share papers, ask and answer questions, and find collaborators. According to a study by Nature and an article in Times Higher Education , it is the largest academic social network in terms of active users.

Curriculum Vitae for R J Robbins

short personal version

Curriculum Vitae for R J Robbins

long standard version

RJR Picks from Around the Web (updated 11 MAY 2018 )