Abstract:

Objective: Enterococci are important nosocomial agents and due to their potential antimicrobial resistance they have a significant role in the dissemination of resistance genes. Currently, these species are described as healthcare concern. The aim of this study was to determine vanA and vanB genes in vancomycin resistant enterococci (VRE) strains isolated from the various clinical samples in the hospitals in Iran. Methods: Susceptibility of 235 strains to vancomycin was screened as minimum inhibitory concentration (MIC) by E-test. The genes encoding modifying vancomycin precursor's dipeptide termini named as vanA and vanB genes were targeted by Taq Man real time PCR assay in vancomycin resistant and vancomycin intermediate resistant Enterococcus faecalis and Enterococcus faecium strains. Results: A total of 235 enterococci were isolated from the clinical specimens. One hundred and ninety three (82.1%) of them were defined as E. faecalis, 33 (14.0%) E. faecium, 1/235 (0.4%) E. avium, 1/235 (0.4%) E. raffinosus and 7/235 (3.0%) E. galinarium. The prevalence of vancomycin resistance was 13.6% (32/235) consisting of 18/235 (7.7%) E. faecalis and 6.0% (14/235) E. faecium. Among the 32 VRE strains, a total of 36 vanA and vanB genes were detected (some isolates had both vanA and vanB genes). These resistance genes were not detected in 5 out of 32 (15.6%) isolates. Conclusion: E. faecalis was more common in clinical samples and vanA (58.3%) gene was the predominant gene among the VRE isolates. The current study showed that Taq Man real time PCR assay is the useful, precise and rapid detection of vancomycin resistance genes.

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