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Detection of Biofilm Forming Bacterial Communities from Urinary Catheter of Patients with Change in Its Antibiotic Susceptibility Pattern and Triclosan Effect from Different Hospitals of Amravati City Maharashtra, India  [PDF]
Anjali A. Tiwari, Niraj Ghnawate
Open Journal of Medical Microbiology (OJMM) , 2017, DOI: 10.4236/ojmm.2017.73005
Abstract: Purpose: Bacterial biofilm develop on the surfaces of urinary catheter and proceed to cause full blown bacterial infections and sepsis. Urinary catheters, infection rates increase with the duration of catheterization at rates of per day with virtually all of those who undergo long-term catheterization becoming infected. Also antibiotics results in the adaptation and development of resistance leading to treatment failure, prolonged hospitalization, increased costs of care, and increased mortality. Methods: In the present study total 200 used urinary catheters were studied from the different hospitals of Amravati city in 2015-2016. Different bacterial uropathogens were isolated by conventional method and biofilm formation was studied by tissue culture plate (TCP). Antibiotic sensitivity was performed by disc diffusion method. Minimum inhibitory concentration (MIC) and Minimum biofilm eradicating concentration (MBEC) of triclosan was determined by TCP. Results: Out of total samples 93% are contaminated. Around 59% urinary catheters contain mixed consortia. Pseudomonas aeruginosa was found to be the strong biofilm forming and multidrug resistant organism. The most effective drug over seven bacteria isolates were chloramphenicol. Triclosan was used to test against the strong and moderate biofilm forming isolates the MIC of triclosan ranged between 1.5 and 1000 μg/ml and MBEC was between 800 and 3200 μg/ml Conclusions: From the study it was concluded that female are more prone to be infected with catheter associated infection. Pseudomonas aeruginosa was found to be deadly caused of infection, as it is highly resistant to antibiotics. Also triclosan showed effective result on the bacterial uropathogens.
Subinhibitory Concentrations of Triclosan Promote Streptococcus mutans Biofilm Formation and Adherence to Oral Epithelial Cells  [PDF]
Telma Blanca Lombardo Bedran, Louis Grignon, Denise Palomari Spolidorio, Daniel Grenier
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0089059
Abstract: Triclosan is a general membrane-active agent with a broad-spectrum antimicrobial activity that is commonly used in oral care products. In this study, we investigated the effect of sub-minimum inhibitory concentrations (MICs) of triclosan on the capacity of the cariogenic bacterium Streptococcus mutans to form biofilm and adhere to oral epithelial cells. As quantified by crystal violet staining, biofilm formation by two reference strains of S. mutans was dose-dependently promoted, in the range of 2.2- to 6.2-fold, by 1/2 and 1/4 MIC of triclosan. Observations by scanning electron microscopy revealed the presence of a dense biofilm attached to the polystyrene surface. Growth of S. mutans in the presence of triclosan at sub-MICs also increased its capacity to adhere to a monolayer of gingival epithelial cells. The expression of several genes involved in adherence and biofilm formation in S. mutans was investigated by quantitative RT-PCR. It was found that sub-MICs of triclosan significantly increased the expression of comD, gtfC, and luxS, and to a lesser extent of gtfB and atlA genes. These findings stress the importance of maintaining effective bactericidal concentrations of therapeutic triclosan since sub-MICs may promote colonization of the oral cavity by S. mutans.
Modern Technologies of Bacterial Biofilm Study  [PDF]
I.V. Chebotar,A.G. Pogorelov,V.A. Yashin,E.L. Guryev
Sovremennye Tehnologii v Medicine , 2013,
Abstract: The aim of the investigation was to estimate the availability of new biomedical technologies to identify bacterial biofilms and evaluate them on a staphylococcal biofilm model.Materials and Methods. We studied staphylococcal biofilms by mass spectrometry, laser scanning (confocal) microscopy, scanning electron microscopy, enzymatic and oxidative destruction of extracellular biofilm matrix. Results. We demonstrated the capabilities of new biomedical technologies in identification of generic specificity of biofilm-forming staphylococcus, and in detection of the necessary characteristics of staphylococcal biofilm. Mass spectrometry enabled to identify the type of biofilm-forming staphylococcus (Staphylococcus aureus). Microscopic study using laser scanning confocal microscopic technique revealed 3-demensional organization typical of S. aureus biofilms. Scanning electron microscopy enabled to visualize the structures of extracellular S. aureus biofilm matrix. The extracellular matrix of the test biofilm was found to be formed of DNA-protein complexes.
Microfluidic Approaches to Bacterial Biofilm Formation  [PDF]
Junghyun Kim,Hee-Deung Park,Seok Chung
Molecules , 2012, DOI: 10.3390/molecules17089818
Abstract: Bacterial biofilms—aggregations of bacterial cells and extracellular polymeric substrates (EPS)—are an important subject of research in the fields of biology and medical science. Under aquatic conditions, bacterial cells form biofilms as a mechanism for improving survival and dispersion. In this review, we discuss bacterial biofilm development as a structurally and dynamically complex biological system and propose microfluidic approaches for the study of bacterial biofilms. Biofilms develop through a series of steps as bacteria interact with their environment. Gene expression and environmental conditions, including surface properties, hydrodynamic conditions, quorum sensing signals, and the characteristics of the medium, can have positive or negative influences on bacterial biofilm formation. The influences of each factor and the combined effects of multiple factors may be addressed using microfluidic approaches, which provide a promising means for controlling the hydrodynamic conditions, establishing stable chemical gradients, performing measurement in a high-throughput manner, providing real-time monitoring, and providing in vivo-like in vitro culture devices. An increased understanding of biofilms derived from microfluidic approaches may be relevant to improving our understanding of the contributions of determinants to bacterial biofilm development.
Triclosan causes toxic effects to algae in marine biofilms, but does not inhibit the metabolic activity of marine biofilm bacteria  [PDF]
C. Henrik Johansson,Lisa Janmar,Thomas Backhaus
PeerJ , 2015, DOI: 10.7287/peerj.preprints.371v1
Abstract: Effects of the antimicrobial agent triclosan to natural periphyton communities (biofilms, comprising primarily microalgae and bacteria) were assessed in two independent experiments during spring and summer. For that purpose a semi-static test system was used in which periphyton was exposed to a concentration range of 5 – 9 054 nmol/L triclosan. Effects on algae were analyzed as content and composition of photosynthetic pigments. The corresponding EC50 values were 39.25 and 302.45 nmol/L for the spring and summer experiment respectively. Effects on periphytic bacteria were assessed as effects on carbon utilization patterns, using Biolog Ecoplates. No inhibition of either total carbon utilization or functional diversity was observed, indicating a pronounced triclosan tolerance of the marine bacteria. In contrast, a small stimulation of the total carbon utilization was observed at triclosan concentrations exceeding 100 nmol/L.
Bacterial Biofilm Formation on Resorbing Magnesium Implants  [PDF]
Olga Charyeva, Jessica Neilands, Gunnel Svens?ter, Ann Wennerberg
Open Journal of Medical Microbiology (OJMM) , 2015, DOI: 10.4236/ojmm.2015.51001
Abstract: Background: Implant-associated infections are a result of bacterial adhesion to an implant surface and subsequent biofilm formation at the implantation site. This study compares different magnesium materials based on their ability to resist bacterial adhesion as well as further biofilm formation. Material and Methods: The surfaces of four magnesium-based materials (Mg2Ag, Mg10Gd, WE43 and 99.99% pure Mg) were characterized using atomic force microscope. In addition, the samples were tested for their ability to resist biofilm formation. Planktonic bacteria of either S. epidermidis or E. faecalis were allowed to adhere to the magnesium surfaces for two hour followed by rinsing and, for S. epidermidis, further incubation of 24, 72 and 168 h was carried out. Results: E. faecalis had a significantly stronger adhesion to all magnesium surfaces compared to S. epidermidis (p = 0.001). Biofilm growth of S. epidermidis was different on various magnesium materials: the amount of bacteria increased up to 72 h but interestingly a significant decrease was seen at 168 h on Mg2Ag and WE43 surfaces. For pure Mg and Mg10Gd the biofilm formation reached plateau at 72 h. Surface characteristics of resorbable magnesium materials were changing over time, and the surface was generally less rough at 168 h compared to earlier time points. No correlation was found between the surface topology and the amount of adherent bacteria. Conclusion: In early stages of biofilm adhesion, no differences between magnesium materials were observed. However, after 72 h Mg2Ag and WE43 had the best ability to suppress S. epidermidis’ biofilm formation. Also, bacterial adhesion to magnesium materials was not dependent on samples’ surface topology.
Bacterial Extracellular Polysaccharides Involved in Biofilm Formation  [PDF]
Barbara Vu,Miao Chen,Russell J. Crawford,Elena P. Ivanova
Molecules , 2009, DOI: 10.3390/molecules14072535
Abstract: Extracellular polymeric substances (EPS) produced by microorganisms are a complex mixture of biopolymers primarily consisting of polysaccharides, as well as proteins, nucleic acids, lipids and humic substances. EPS make up the intercellular space of microbial aggregates and form the structure and architecture of the biofilm matrix. The key functions of EPS comprise the mediation of the initial attachment of cells to different substrata and protection against environmental stress and dehydration. The aim of this review is to present a summary of the current status of the research into the role of EPS in bacterial attachment followed by biofilm formation. The latter has a profound impact on an array of biomedical, biotechnology and industrial fields including pharmaceutical and surgical applications, food engineering, bioremediation and biohydrometallurgy. The diverse structural variations of EPS produced by bacteria of different taxonomic lineages, together with examples of biotechnological applications, are discussed. Finally, a range of novel techniques that can be used in studies involving biofilm-specific polysaccharides is discussed.
The Natural Antimicrobial Carvacrol Inhibits Quorum Sensing in Chromobacterium violaceum and Reduces Bacterial Biofilm Formation at Sub-Lethal Concentrations  [PDF]
Sara A. Burt, Victoria T. A. Ojo-Fakunle, Jenifer Woertman, Edwin J. A. Veldhuizen
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093414
Abstract: The formation of biofilm by bacteria confers resistance to biocides and presents problems in medical and veterinary clinical settings. Here we report the effect of carvacrol, one of the major antimicrobial components of oregano oil, on the formation of biofilms and its activity on existing biofilms. Assays were carried out in polystyrene microplates to observe (a) the effect of 0–0.8 mM carvacrol on the formation of biofilms by selected bacterial pathogens over 24 h and (b) the effect of 0–8 mM carvacrol on the stability of pre-formed biofilms. Carvacrol was able to inhibit the formation of biofilms of Chromobacterium violaceum ATCC 12472, Salmonella enterica subsp. Typhimurium DT104, and Staphylococcus aureus 0074, while it showed no effect on formation of Pseudomonas aeruginosa (field isolate) biofilms. This inhibitory effect of carvacrol was observed at sub-lethal concentrations (<0.5 mM) where no effect was seen on total bacterial numbers, indicating that carvacrol's bactericidal effect was not causing the observed inhibition of biofilm formation. In contrast, carvacrol had (up to 8 mM) very little or no activity against existing biofilms of the bacteria described, showing that formation of the biofilm also confers protection against this compound. Since quorum sensing is an essential part of biofilm formation, the effect of carvacrol on quorum sensing of C. violaceum was also studied. Sub-MIC concentrations of carvacrol reduced expression of cviI (a gene coding for the N-acyl-L-homoserine lactone synthase), production of violacein (pigmentation) and chitinase activity (both regulated by quorum sensing) at concentrations coinciding with carvacrol's inhibiting effect on biofilm formation. These results indicate that carvacrol's activity in inhibition of biofilm formation may be related to the disruption of quorum sensing.
Towards the identification of the common features of bacterial biofilm development
International Microbiology , 2006,
Abstract: microorganisms can live and proliferate as individual cells swimming freely in the environment, or they can grow as highly organized, multicellular communities encased in a self-produced polymeric matrix in close association with surfaces and interfaces. this microbial lifestyle is referred to as biofilms. the intense search over the last few years for factors involved in biofilm development has revealed that distantly related bacterial species recurrently make use of the same elements to produce biofilms. these common elements include a group of proteins containing ggdef/eal domains, surface proteins homologous to bap of staphylococcus aureus, and some types of exopolysaccharides, such as cellulose and the poly-b-1,6-n-acetylglucosamine. this review summarizes current knowledge about these three common elements and their role in biofilm development.
A Communal Bacterial Adhesin Anchors Biofilm and Bystander Cells to Surfaces  [PDF]
Cedric Absalon,Katrina Van Dellen,Paula I. Watnick
PLOS Pathogens , 2011, DOI: 10.1371/journal.ppat.1002210
Abstract: While the exopolysaccharide component of the biofilm matrix has been intensively studied, much less is known about matrix-associated proteins. To better understand the role of these proteins, we undertook a proteomic analysis of the V. cholerae biofilm matrix. Here we show that the two matrix-associated proteins, Bap1 and RbmA, perform distinct roles in the biofilm matrix. RbmA strengthens intercellular attachments. In contrast, Bap1 is concentrated on surfaces where it serves to anchor the biofilm and recruit cells not yet committed to the sessile lifestyle. This is the first example of a biofilm-derived, communally synthesized conditioning film that stabilizes the association of multilayer biofilms with a surface and facilitates recruitment of planktonic bystanders to the substratum. These studies define a novel paradigm for spatial and functional differentiation of proteins in the biofilm matrix and provide evidence for bacterial cooperation in maintenance and expansion of the multilayer biofilm.
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