Molecular analyses of community-acquired Staphylococcus epidermidis biofilm development, molecular virulence, and...

Staphylococcus epidermidis generally causes skin and soft tissue infections. Control and treatment of infections caused by S. epidermidis require in-depth analyses of its genotypic traits and patterns of their antibiotic susceptibility.

100 S. epidermidis isolates were obtainedfrom community setting in Midnapore, West Bengal, India. Different biochemical and PCR-based analyses could identify the presumed S. epidermidis phenotypically, and subsequently their genotypic makeup. Besides that, the isolates were studied for presence of virulence genes and biofilm formation capabilities. Majority of the isolates (63%) were found as possessing moderate biofilm-forming capabilities; only 23% and 14% had high and low biofilm capacities, respectively. Intercellular adhesion (ica) operon involved in biofilm signalling, screened using PCR, revealed the presence of two most-prevalent icas, accounting 80.7% (icaB) and 86.5% (sarA). Only two isolates were tested positive for all of the six known virulence genes using PCR. Haemolysin-encoding genes had the greatest prevalence rates with 92.3 and 94.2% of isolates to be found positive for the hla and hlb genes, respectively. Two strains (3.8%) could be found with the staphylococcal toxin-encoding genes see, seg, and sei. With multiple antibiotic resistance indices ranging from 0.38 to 0.75, S. epidermidis isolates exhibited low resistance to linezolidand levofloxacin.

Conventional antibiotic use was associated with higher percentages of multi-drug resistance outbreaks. The identification of staphylococcal toxin in community has raisedworries about the emergence of new variants. The high frequency of ica operons is believed to drive further research into targeting these genes as alternative therapeutic options.