بررسي الگوي مقاومت آنتي بيوتيكي و تعيين ژنهاي مقاومت van A و van B در ميان سويه هاي انتروككي جداشده از مراكز درماني و آزمايشگاه هاي شهر تهران

Antibiotic Resistance and Detection of vanA , vanB Resistance Genes in Enterococcus spp. Isolated from Hospitals and Medical Laboratories in Tehran

Background and objectives: Enterococci are members of the normal gut flora of animals and humans and have an important role in ndocardithis and urethrithis. These groups of microorganism are released into the environment directly or via sewage outlets. Enterococci are important not only because they are a leading cause of nosocomial infections, but also because they may have a significant role in dissemination and persistence of antibiotic resistance. The aim of the study was to detect and analyze antibiotic resistance pattern and vancomycin resistance genes, vanA and vanB among enterococci isolated from hospitals and laboratories in Tehran. Materials and methods: 540 isolates of Enterococci were identified at the species level by the common biochemical tests and. Antibiotic susceptibility test to 7 antibiotics vancomycin, gentamicin, tetracycline, ciprofloxacin, ampicillin, erythromycin and chloramphenicol was done by disc diffusion. MIC to vancomycin was also done using broth micro dilution assay. vanA and vanB genes were detected among VRE and VIE isolates. Results: The biochemical tests showed that 68 and 32% of isolates were E. faecalis and E. faecium respectively. The antibiotic resistance of the isolates were as follow: 8, 8, 53, 50, 65, 52 and 6% of the isolates were resistant to vancomycin, gentamicin, tetracycline, ciprofloxacin, erythromycin, ampicillin and chloramphenicol respectively. MIC test showed that 46 of the isolates were highly resistant to vancomycin (MIC>512 jug/ml). 100% and 2% of Vancomycin Resistant Enterococcus isolates had vanA and vanB gene respectively. Conclusion: The distribution of enterococci was limited to E. faecium. Resistance to vancomycin and gentamicin was less than other antibiotics, and resistance to erythromycin and ampicillin was higher. Distribution of vanA and vanB genes was similar to other concerns from Iran and other countries.