Genotypic variations of virulent genes in Enterococcus faecium and Enterococcus faecalis isolated from three hospitals in Malaysia.

BACKGROUND The genus Enterococcus is of increasing significance as a cause of nosocomial infections, and this trend is exacerbated by the development of antibiotic resistance. OBJECTIVES The aim of the present study was to estimate the potential virulence factors in enterococci and to ascertain their prevalence in Malaysian hospitals. MATERIAL AND METHODS The study comprised 222 enterococcal strains isolated from blood, urine, exudates, sputum, stool and body fluid. These strains were collected from patients staying in three referral hospitals in Malaysia. All isolates were identified to the species level, and their MIC of vancomycin was determined using E test strips. Specific primers were designed for detection of the five potential virulence genes (gelE, PAI, esp, ace, and sprE) by PCR assay. RESULTS Different patterns and frequency of virulence determinants were found for the E. faecalis and E. faecium isolates. E. faecalis isolates had more virulence determinants than E. faecium isolates. Clinical enterococcal isolates were found to possess more virulence determinants than enterococci isolated from faecal samples. The esp gene is significantly more common (p = 0.049) in vancomycin-resistant strains (85.7%) than in vancomycin-sensitive strains (44.2%). All of the vancomycin-resistant isolates were isolated from faecal samples. None of the classical virulence factors were found in 11% of enterococcal isolates, while all five virulence genes were found in 21% of enterococcal isolates. CONCLUSIONS All the virulence genes considered in this study were important in the pathogenesis of enterococcal infections and further studies including more virulence genes and epidemiological data will be necessary in order to analyze the association and role of virulence genes in the pathogencity of enterococci.