Epidemiologic evaluation of Vancomycin Resistant genes in Enterococcus spp. isolated from clinical samples

Background & Objectives: Isolation of vancomycin resistant Enterococcus from clinical samples is very important. The aim of this study was evaluation of phenotype and genotype of van genes in vancomycine resistant Enterococcus. Materials and Methods: 411 Enterococcus isolates were collected from selected Tehran’s hospitals between March 2004 and December 2007. The enterococcal isolates were identified by biochemical confirmation tests. Resistance of each isolate to vancomycin determined by disk diffusion and agar dilution test. The presence of the vanA, B, C, D, E resistance gene was assessed by PCR. Results: 185(45%) and 23(5.6%) with disc-diffusion method and agar-dilution method were resistant to vancomucin (VRE) and all of VREs were Enterococcus faecium. 12 (52.2%), 7(30.4%) of the VRE isolates had vanA, vanB and 3(13%) had both of vanA and vanB gene. Conclusion: Most important mechanism for high level resistance to vancomycin is presence of van genes and these genes can transfer between Enterococci. Significance of investigation in molecular level of resistance to vancomycin was due to relation between phenotypic resistant and presence of van genes.