Comparative study among clinical and commensal isolates of Enterococcus faecalis for presence of esp gene and biofilm production

Abstract

Introduction: Because of increasing difficulty in treating enterococcal infections, effort is being devoted to understanding factors that are responsible for causing nosocomial infection, with a focus toward targeting these factors with new therapeutics. Evidence has emerged that the esp gene mediates biofilm formation in vitro, which helps the organism colonize and cause infection.

Methodology: This study was conducted over a four-year period in a tertiary-care hospital. There were 200 clinical pathogenic strains isolated from nosocomial infections and 100 commensals from stool specimens of healthy individuals. The study compared the production of biofilm and detection of the esp gene among clinical and commensal isolates.

Results: Among 200 clinical isolates of Enterococcus faecalis 65 (32.5%) isolates were positive for biofilm production and 60 (30%) for the esp gene by PCR. Among 100 commensal isolates, 16     (8%) and 14 (7%) were positive for biofilm formation and the esp gene, respectively. Five clinical and two commensal isolates produced biofilm without any amplification of the esp gene.

Conclusion: The study shows a significant difference in production of biofilm and presence of the esp gene between clinical and commensal isolates (P < 0.002). Therefore, it can be concluded that biofilm production has an important role in causing nosocomial infection. Although detection of the esp gene correlates with biofilm production, it may not be the only factor determining the formation of biofilm since few isolates produced biofilm without the esp gene. Strains isolated from indwelling medical devices showed high production of biofilm and esp gene.