Prevalence of Virulence Factors and Vancomycin-Resistant Genes among Enterococcus faecalis and E. faecium Isolated from Clinical Specimens

The aim of this study was to determine the occurrence of virulence determinants and vancomycin- resistant genes among Enterococcus faecalis and E. faecium obtained from various clinical sources.
The study was performed on the 280 enterococcal isolated from clinical specimens in Hamadan hospitals, western Iran in 2012-14. Antibiotic susceptibility testing was performed using disk diffusion and Minimal Inhibitory Concentration (MIC) methods. The presence of vancomycin-resistant genes and virulence genes was investigated using PCR.
Totally 280 enterococcal isolates were identified as follows: E. faecalis (62.5%), E. faecium (24%) and Enterococcus spp (13.5%). The results of antibiotic susceptibility testing showed that resistance rates to vancomycin and teicoplanin in E. faecalis and E. faecium isolates were 5% and 73%, respectively. Of Sixty vancomycin-resistant Enterococci strains, fifty-one isolates were identified as E. faecium (VREfm) and nine as E. faecalis (VREfs). Prevalence of esp, hyl, and asa1 genes were determined as 82%, 71.6%, and 100%, respectively in E. faecium strains; and 78%, 56/6%, and 97%, respectively in E. faecalis strains.
The increased frequency of VREF, as seen with rapid rise in the number of vanA isolates should be considered in infection control practices.