Vancomycin-resistant Enterococcus species: Antimicrobial resistance and virulence genes profile

Abstract

BackgroundIn this study, antimicrobial resistance, virulence genes profile, and genetic relatedness among Enterococcus isolates obtained from a hospital in Ardabil were studied. MethodsE. faecalis and E. Faecium isolates were identified using microbiological and molecular methods. Vancomycin minimum inhibitory concentrations (MICs) were determined by agar dilution assay. Antimicrobial resistance pattern was evaluated by the disk diffusion method. Vancomycin resistance and virulence genes were detected by polymerase chain reaction (PCR). Genetic relatedness among the vancomycin-resistant Enterococcus (VRE) isolates was evaluated by enterobacterial repetitive intergenic consensus (ERIC)-PCR. ResultsTotally, 96 Enterococcus isolates were collected. Of these, 72 (75%) and 24 (25%) cases belonged to E. faecalis and E. faecium species, respectively. One (1.4%) and 10 (41.7%) isolates of E. faecalis and E. faecium were found to be resistant to vancomycin, respectively. All the VRE isolates were positive for the vanA gene. Both E. faecalis and E. faecium species showed high rates of resistance to erythromycin (58.3%, 87.5%), tetracycline (50%, 79.16%), rifampicin (47.2%, 95.8%), and ciprofloxacin (38.9%, 75%), respectively. The resistance rates were significantly higher in VRE isolates compared to vancomycin-sensitive isolates (P ≤ 0.05). The lowest values were observed for resistance to nitrofurantoin (1.4% and 0.0%) and chloramphenicol (1.4% and 12.5%) in E. faecalis and E. faecium isolates, respectively. Most of the VRE isolates were recovered from urine specimens obtained from patients admitted to internal ward. gelE and asa1 were the major virulence genes in VRE isolates. High genetic diversity was observed among VRE isolates. ConclusionThe high prevalence of genetically versatile and multidrug resistant E. faecium in our study indicates the need for careful infection control precautions.