ABSTRACT
The objective of this study was to detect the association of biofilm formation with IS256 among clinical and carrier isolates of methicillin-resistant Staphylococcus epidermidis (MRSE). A total of 71 MRSE isolates were included in this study. Phenotypic detection of biofilm formation was done by Congo red agar method. Detection of genes associated with biofilm formation (icaAD, aap and atlE) and insertion sequence IS256 was done by polymerase chain reaction. Of the 71 MRSE isolates,19/40 (47.5%) clinical isolates from hospital settings and 11/31 (35.5%) carrier isolates from community settings respectively were found to be positive for all the three genes tested, namely, icaAD+, aap+ and atlE+ genes. Nearly 80% of clinical isolates were found to harbour IS256, whereas only 13% of community isolates harboured IS256.
ABSTRACT
The present report aimed to perform a molecular epidemiological survey by investigating the presence of virulence factors in E. faecalis isolated from different human clinical (n = 57) and food samples (n = 55) in Porto Alegre, Brazil, collected from 2006 to 2009. In addition, the ability to form biofilm in vitro on polystyrene and the β-haemolytic and gelatinase activities were determined. Clinical strains presented a higher prevalence of aggregation substance (agg), enterococcal surface protein (esp) and cytolysin (cylA) genes when compared with food isolates. The esp gene was found only in clinical strains. On the other hand, the gelatinase (gelE) and adherence factor (ace) genes had similar prevalence among the strains, showing the widespread occurrence of these virulence factors among food and clinical E. faecalis strains in South Brazil. More than three virulence factor genes were detected in 77.2% and 18.2% of clinical and food strains, respectively. Gelatinase and β-haemolysin activities were not associated with the presence of gelE and cylA genes. The ability to produce biofilm was detected in 100% of clinical and 94.6% of food isolates, and clinical strains were more able to form biofilm than the food isolates (Student's t-test, p < 0.01). Results from the statistical analysis showed significant associations between strong biofilm formation and ace (p = 0.015) and gelE (p = 0.007) genes in clinical strains. In conclusion, our data indicate that E. faecalis strains isolated from clinical and food samples possess distinctive patterns of virulence factors, with a larger number of genes that encode virulence factors detected in clinical strains.
Subject(s)
Humans , Bacterial Proteins/genetics , Enterococcus faecalis/genetics , Food Microbiology , Gram-Positive Bacterial Infections/microbiology , Virulence Factors/genetics , Brazil , Biofilms/growth & development , Enterococcus faecalis/isolation & purification , Enterococcus faecalis/physiology , Gelatinases/analysis , HemolysisABSTRACT
The production of extracellular vesicles is a ubiquitous process in both Gram-negative and Gram-positive bacteria. Gram-negative bacteria produce and secrete outer membrane vesicles during in vitro culture and in vivo infection and their contribution to bacterial pathogenesis has been well characterized. However, little is known about extracellular vesicles in Gram-positive bacteria. Until now, only few Gram-positive bacterial species, Staphylococcus aureus, Bacillus anthracis, B. cereus, and B. subtilis, have been found to produce membrane vesicles (MVs), but their contribution to bacterial pathogenesis has not been understood. Here, I discuss S. aureus MVs in terms of MV production, interaction of MVs with host cells, and immune response against MVs to understand its potential role in S. aureus pathogenesis.