Evaluation of drug sensitivity of Entrococcus faecium and Entrococcus faecalis Strains and Detection of VanA/B Genes in Vancomycin Resistance Isolated by PCR Method

Enterococci, as the major cause of nosocomial infections, have been shown to have an increase in drug resistance during the past two decades. The Entrococcal emergence of Vancomycin-resistant is very important nowadays. The purpose of this study was to determine the drug sensitivity of Enterococcus faecalis and Enterococcus faecium species against Vancomycin, Tetracycline, Gentamicin, Erythromycin and the presence of Van A / B genes in resistant Enterococci to Vancomycin. A total of 189 samples, including urine, blood, wound and stool were collected from patients referred to Masoud Medical laboratory in Tehran, Iran, during years 2011-2012. Strains of Enterococci were identified by standard methods and antibiotic susceptibility testing was performed by disk diffusion according to standard methods (CLSI). The test was carried out on the samples resistant to Vancomycin for determining MIC levels. The frequencies of VanA and VanB were studied by using of PCR. A total of 89 Enterococcus were isolated in this study. In this study, 89 Enterococcus were obtained, of which 8 were resistant to Vancomycin based on the disk diffusion method. All Vancomycin resistant isolates showed VanA gene, while none of them (0%) carried VanB gene. The results obtained by this study indicated that Vancomycin-resistant Enterococci isolates did not commonly carry the VanA gene. However, VanA gene was fairly frequent as it was detected in 8 strains, while VanB gene was found in none of the strains.