Comparative Study for the Presence of Enterococcal Virulence Factors Gelatinase, Hemolysin and Biofilm Among Clinical and Commensal Isolates of Enterococcus Faecalis

BACKGROUND: Biofilm production, gelatinase and hemolysin are the potential virulence factors of Enterococci. Gelatinase and hemolysin producing strains of Enterococcus Faecalis have been shown to cause severe infections in animal models. Biofilm production has been shown to enhance the persistence of E. faecalis in urinary bladder and other medical indwelling devices infections. AIMS: To compare the presence of gelatinase, hemolysin and biofilm formation among clinical and commensal isolates and to study the co-relation between virulence factors with respect to different clinical specimens. SETTINGS AND DESIGN: During the study period of 2 years from July 2004 to July 2006, 200 clinical isolates from nosocomial infections and 100 commensal isolates of E. faecalis were taken for the study. MATERIALS AND METHODS: The clinical and commensal isolates were tested for the presence of gelatinase, hemolysin and biofilm and compared. The presence of these virulence factors among different clinical isolates was also studied. STATISTICAL ANALYSIS: Chi-square and likelihood ratio analysis were carried out using SSPS version 5.1 software. RESULTS: The clinical isolates produced 39, 16.5 and 32.5% of gelatinase, hemolysin and biofilm, respectively, as compared to 31, 19 and 16% produced by the commensal isolates, respectively. Endotracheal tube infection, urinary tract infection, umbilical catheter tip infected isolates produced 60.8, 86.6 and 100% biofilm, respectively. CONCLUSION: Significant difference in the production of biofilm (P<0.001) was noted between clinical and commensal isolates. Organism isolated from medically indwelling devices produced high amount of biofilm, confirming its role in colonization and causing nosocomial infections.