Incidence of van A, B, C, D, E in vancomycin resistant Enterococcus isolated from fecal flora in Tehran

Vancomycin-resistant enterococci (VRE) have emerged worldwide and have become an increasing problem in clinical settings. Acquired glycopeptide resistance in Enterococcus species is due to the acquisition of van A, van B, van D, van C and van E genes, resulting in the production of peptidoglycan precursors with reduced affinity for glycopeptide antibiotics. The origin of these van genes is still unknown, but recent studies have indicated that van B resistance in enterococci might arise from gene transfer from the human bowel flora. In this study, we investigated the presence of Enterococcus-associated van A, van B, van C, van D, van E genes in the feces of hospitalized patients. To determine the prevalence of vancomycin-resistant enterococci (VRE) fecal colonization of hospitalized patients, 422 Enterococcus spp. isolated from stool of patients in Amiralam hospital. Disk diffusion method was used to detect resistance to vancomycin. The MICs of vancomycin were determined by the agar dilution method. The presence of van A, B, C, D and E genes were assassed by PCR analysis. PCR was positive for van A for 6 out of 10 (60%) and van B for 4 out of 10 (40%) of VRE strains. Among the van positive enterococci, two (20%) specimens contained both van A and van B gene, whereas no van C, D and E positive enterococcal isolates were identified from these specimens. The MIC of VRE isolates were between 512- 1024 μg/ml. Our results showed that most glycopeptide resistant Enterococcus isolated from stool of hospitalized patients carried van A and van B. It is also possible that frequency of infections caused by glycopeptide-resistant enterococci will increase in our geographical area.