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Biofilm Cells (biofilm + cell)

Distribution by Scientific Domains

Medical Sciences	55%
Life Sciences	44%

Selected Abstracts

Antibacterial effects of MDPB against anaerobes associated with endodontic infections

INTERNATIONAL ENDODONTIC JOURNAL, Issue 8 2010
N. Izutani
Izutani N, Imazato S, Noiri Y, Ebisu S. Antibacterial effects of MDPB against anaerobes associated with endodontic infections. International Endodontic Journal. Abstract Aim, To investigate the antibacterial effects of 12-methacryloyloxydodecylpyridinium bromide (MDPB), an antibacterial monomer synthesized by combining quaternary ammonium with a methacryloyl group, against three anaerobes associated with endodontic infections using planktonic and biofilm cells. Methodology, The antibacterial activity of unpolymerized MDPB against Enterococcus faecalis, Fusobacterium nucleatum and Prevotella nigrescens was examined by agar-disc diffusion tests and determination of the minimum inhibitory/bactericidal concentrations (MIC/MBC). Rapid killing effects of MDPB against three bacteria in planktonic form were examined by a cell number counting method, and those against biofilm cells were assessed by a viability staining method. Results, MDPB demonstrated inhibition against all of the bacteria tested by agar-disc diffusion tests. The MIC/MBC values of MDPB for the three anaerobes were much smaller than those of other resin monomers, although greater compared with those of cetylpyridinium chloride or chlorhexidine diacetate for E. faecalis and F. nucleatum. Significant reduction in viable planktonic cells was obtained by contact with 250 ,g mL,1 of MDPB for 20 s (P < 0.05, Fisher's PLSD tests), and 40 s contact with 500 ,g mL,1 or 20 s contact with 1000 ,g mL,1 of MDPB resulted in more than 90% killing. Biofilm cells of all species were completely killed by application of 1000 ,g mL,1 of MDPB for 60 s. Conclusion, MDPB was found to have strong antibacterial effects against E. faecalis, F. nucleatum and P. nigrescens, and such effects were rapidly exhibited even against biofilm cells, suggesting the usefulness of application of MDPB to resin-based materials for root canal filling. [source]

Pseudomonas fluorescens' view of the periodic table

ENVIRONMENTAL MICROBIOLOGY, Issue 1 2008
Matthew L. Workentine
Summary Growth in a biofilm modulates microbial metal susceptibility, sometimes increasing the ability of microorganisms to withstand toxic metal species by several orders of magnitude. In this study, a high-throughput metal toxicity screen was initiated with the aim of correlating biological toxicity data in planktonic and biofilm cells to the physiochemical properties of metal ions. To this end, Pseudomonas fluorescens ATCC 13525 was grown in the Calgary Biofilm Device (CBD) and biofilms and planktonic cells of this microorganism were exposed to gradient arrays of different metal ions. These arrays included 44 different metals with representative compounds that spanned every group of the periodic table (except for the halogens and noble gases). The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum biofilm eradication concentration (MBEC) values were obtained after exposing the biofilms to metal ions for 4 h. Using these values, metal ion toxicity was correlated to the following ion-specific physicochemical parameters: standard reduction-oxidation potential, electronegativity, the solubility product of the corresponding metal,sulfide complex, the Pearson softness index, electron density and the covalent index. When the ions were grouped according to outer shell electron structure, we found that heavy metal ions gave the strongest correlations to these parameters and were more toxic on average than the other classes of the ions. Correlations were different for biofilms than for planktonic cells, indicating that chemical mechanisms of metal ion toxicity differ between the two modes of growth. We suggest that biofilms can specifically counter the toxic effects of certain physicochemical parameters, which may contribute to the increased ability of biofilms to withstand metal toxicity. [source]

Antibacterial effects of MDPB against anaerobes associated with endodontic infections

Effectiveness of ozone against endodontopathogenic microorganisms in a root canal biofilm model

INTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2009
K. C. Huth
Abstract Aim, To assess the antimicrobial efficacy of aqueous (1.25,20 ,g mL,1) and gaseous ozone (1,53 g m,3) as an alternative antiseptic against endodontic pathogens in suspension and a biofilm model. Methodology,Enterococcus faecalis, Candida albicans, Peptostreptococcus micros and Pseudomonas aeruginosa were grown in planctonic culture or in mono-species biofilms in root canals for 3 weeks. Cultures were exposed to ozone, sodium hypochlorite (NaOCl; 5.25%, 2.25%), chlorhexidine digluconate (CHX; 2%), hydrogen peroxide (H2O2; 3%) and phosphate buffered saline (control) for 1 min and the remaining colony forming units counted. Ozone gas was applied to the biofilms in two experimental settings, resembling canal areas either difficult (setting 1) or easy (setting 2) to reach. Time-course experiments up to 10 min were included. To compare the tested samples, data were analysed by one-way anova. Results, Concentrations of gaseous ozone down to 1 g m,3 almost and aqueous ozone down to 5 ,g mL,1 completely eliminated the suspended microorganisms as did NaOCl and CHX. Hydrogen peroxide and lower aqueous ozone concentrations were less effective. Aqueous and gaseous ozone were dose- and strain-dependently effective against the biofilm microorganisms. Total elimination was achieved by high-concentrated ozone gas (setting 2) and by NaOCl after 1 min or a lower gas concentration (4 g m,3) after at least 2.5 min. High-concentrated aqueous ozone (20 ,g mL,1) and CHX almost completely eliminated the biofilm cells, whilst H2O2 was less effective. Conclusion, High-concentrated gaseous and aqueous ozone was dose-, strain- and time-dependently effective against the tested microorganisms in suspension and the biofilm test model. [source]

Tolerance to the antimicrobial peptide colistin in Pseudomonas aeruginosa biofilms is linked to metabolically active cells, and depends on the pmr and mexAB-oprM genes

MOLECULAR MICROBIOLOGY, Issue 1 2008
Sünje Johanna Pamp
Summary Bacteria living as biofilm are frequently reported to exhibit inherent tolerance to antimicrobial compounds, and might therefore contribute to the persistence of infections. Antimicrobial peptides are attracting increasing interest as new potential antimicrobial therapeutics; however, little is known about potential mechanisms, which might contribute to resistance or tolerance development towards these compounds in biofilms. Here we provide evidence that a spatially distinct subpopulation of metabolically active cells in Pseudomonas aeruginosa biofilms is able to develop tolerance to the antimicrobial peptide colistin. On the contrary, biofilm cells exhibiting low metabolic activity were killed by colistin. We demonstrate that the subpopulation of metabolically active cells is able to adapt to colistin by inducing a specific adaptation mechanism mediated by the pmr operon, as well as an unspecific adaptation mechanism mediated by the mexAB-oprM genes. Mutants defective in either pmr -mediated lipopolysaccharide modification or in mexAB-oprM -mediated antimicrobial efflux were not able to develop a tolerant subpopulation in biofilms. In contrast to the observed pattern of colistin-mediated killing in biofilms, conventional antimicrobial compounds such as ciprofloxacin and tetracycline were found to specifically kill the subpopulation of metabolically active biofilm cells, whereas the subpopulation exhibiting low metabolic activity survived the treatment. Consequently, targeting the two physiologically distinct subpopulations by combined antimicrobial treatment with either ciprofloxacin and colistin or tetracycline and colistin almost completely eradicated all biofilm cells. [source]

Automutanolysin disrupts clinical isolates of cariogenic streptococci in biofilms and planktonic cells

MOLECULAR ORAL MICROBIOLOGY, Issue 6 2009
P. Thanyasrisung
Introduction:, Dental caries remains one of the most common chronic infectious diseases throughout the world. The formation of dental plaque is one of the caries risk factors. As a consequence, the removal of plaque may reduce the incidence of caries development. We identified an autolysin produced by Streptococcus mutans named auto-mutanolysin (Aml). Aml selectively lyses S. mutans and Streptococcus sobrinus. The specificity towards these cariogenic bacteria suggests that Aml may be used to prevent dental caries. Here, with the aim towards therapeutic application, we investigated the lytic activity of Aml against clinical isolates of S. mutans and S. sobrinus using planktonic cells and biofilms. Methods:, Planktonic cell suspensions and biofilms of clinically isolated streptococci were treated with Aml in the absence or the presence of Triton X-100. The lytic activity of Aml was monitored as the change in turbidity. The disruption of biofilms was evaluated by detecting the released DNA by polymerase chain reaction and observing the alteration of optical density of treated biofilms. Results:, Triton X-100 enhances the lytic ability of Aml. Using planktonic cells, Aml had various lysis levels against clinical strains. Repeated Aml treatment showed disruption of the biofilm using the representative clinical strains. Conclusion:, Our study demonstrates that Aml has an ability to lyse planktonic and biofilm cells of clinically isolated mutans streptococci in the presence of Triton X-100. These results suggest the possibility of using Aml as an alternative or additional approach for caries prevention. [source]

Analysis of Streptococcus mutans biofilm proteins recognized by salivary immunoglobulin A

MOLECULAR ORAL MICROBIOLOGY, Issue 5 2009
T. Sanui
Introduction:, The purpose of this study was to examine the Streptococcus mutans biofilm cellular proteins recognized by immunoglobulin A (IgA) in saliva from various caries-defined populations. Methods:, Biofilm and planktonic S. mutans UA159 cells were prepared. The proteins were extracted, separated by two-dimensional gel electrophoresis, transferred to blotting membranes, and probed for IgA using individual saliva samples from three groups of subjects; those who developed 0 caries (no active caries), 5,9 caries (medium), or more than 10 caries (severe) over a 12-month interval. Results:, Several proteins were recognized by salivary IgA in all groups of saliva but spot distribution and intensity varied greatly between the groups, and some proteins were recognized more strongly in biofilm cells than in planktonic culture, and vice versa. Furthermore, 15 proteins were only recognized by saliva from the ,no active caries' group, and four proteins were recognized by saliva samples from subjects in all three groups. Specifically, antigen I/II was recognized less in biofilm cells by caries-free saliva compared with planktonic cells. However, salivary IgA antibody to antigen I/II was absent in blots using saliva from the ,medium caries' and ,severe caries' groups. Conclusion:, The bacterial molecules recognized by caries-free saliva are significant factors for S. mutans caries formation, and their inhibition could be a therapeutic target. In addition, saliva of caries-free subjects includes significant IgA antibody against antigen I/II of S. mutans, indicating a protective mechanism. However, microorganisms may protect themselves from host immune attack by forming biofilms and decreasing expression of antigen I/II. [source]

Genetics and genomics of Candida albicans biofilm formation

CELLULAR MICROBIOLOGY, Issue 9 2006
Clarissa J. Nobile
Summary Biofilm formation by the opportunistic fungal pathogen Candida albicans is a complex process with significant consequences for human health: it contributes to implanted medical device-associated infections. Recent advances in gene expression profiling and genetic analysis have begun to clarify the mechanisms that govern C. albicans biofilm development and acquisition of unique biofilm phenotypes. Such studies have identified candidate adhesin genes, and have revealed that biofilm drug resistance is multifactorial. Newly defined cell,cell communication pathways also have profound effects on biofilm formation. Future challenges include the elucidation of the structure and function of the extracellular exopolymeric substance that surrounds biofilm cells, and the extension of in vitro biofilm observations to newly developed in vivo biofilm models. [source]