Objective: Recently, isolates of Enterococcus faecium have been the leading cause of nosocomial infections worldwide and have at the same time increased multimicrobial resistance which necessitated investigation of many characteristics especially virulence factors in detail for infection control and prevention. The aim of this study was to investigate the virulence factors, resistance genes and genotypic similarities in vancomycin resistant E. faecium (VREfm) isolates.

Material and Methods: The study included 37 Enterococcus faecium isolates obtained from various clinical specimens in microbiology laboratory of Giresun State Hospital. The identification and in vitro antimicrobial susceptibility tests of the isolates were performed using Vitek 2 automated system (BioMérieux, US). The susceptibility to vancomycin and teicoplanin were investigated using broth microdilution method. The presence of vancomycin resistance genes vanA, vanB and virulence genes esp, gelE, hyl, cylA and asa1 were determined by PCR. Biofilm formation was also tested phenotypicaly by Congo Red Agar method. RAPD-PCR was performed to determine the clonal relationship among the isolates.

Results: All of the isolates were resistant to vancomycin, teicoplanin, tetracycline, norfloxacin, eritromycin, ciprofloxacin, ampicillin and susceptible to linezolid. The production of biofilm was observed in all isolates. All of the isolates had the vanA gene and the vanA phenotype characterised by resistance to vancomycin and teicoplanin. esp, gelE and hyl genes were detected in 62.2%, 2.2% and 27% of all the isolates, respectively. vanB, asa1 and cylA genes were not detected in any of the isolates. Genotyping analysis of the isolates by RAPD-PCR identified three main RAPD groups. All of 23 isolates that carried the esp gene also belonged to the dominant RAPD group. When genotypical relationships of all the isolates was evaluated, homogeneity was observed between nearly similar groups.

Conclusions: No relationship was found between specific clones and virulence genes of VREfm; yet high positivity of the isolates for esp gene suggests the impact of this gene on bacterial pathogenicity.