Virulence Determinants and Antimicrobial Resistance Patterns of Vancomycin-resistant Enterococcus faecium Isolated from Different Sources in Southwest Iran

Background: This study aimed to investigate the incidence of antibiotic-resistance and virulence genes in vancomycin-resistant Enterococcus faecium isolated from different sources in southwest Iran from Mar to Sep 2015. Methods: Overall, 120 E. faecium isolates (80 VRE and 40 vancomycin-susceptible enterococci [VSE] isolates) were obtained from four hospitals. The resistance of the VRE isolates was determined by disk diffusion method. Multiplex PCR was performed to detect the virulence genes carried by the E. faecium isolates, namely, enterococcal surface protein (esp), hyaluronidase (hyl), and collagen-binding adhesin (acm). Results: All the VRE isolates exhibited multidrug resistance, with the rates of resistance to ampicillin, erythromycin, and ciprofloxacin reaching high levels. The isolates were least resistant to chloramphenicol and nitrofurantoin, but all of them were susceptible to linezolid. 46.6%, 20.8%, and 86.6% of the E. faecium isolates carried the esp, hyl, and acm genes, respectively. Conclusion: There is a significant difference between the prevalence of esp and hyl genes in the VRE and VSE isolates. In the VRE isolates, the high prevalence of multidrug resistance were found and the difference in the prevalence of esp among various sources was significant. The findings reflected a relationship between the prevalence of esp and hyl and resistance to certain antibiotics.