Enterococcal vanB resistance locus in anaerobic bacteria in human faeces

While developing a rapid method to detect carriers of vancomycin-resistant enterococci (VRE), we found the vans gene by PCR in 13 of 50 human faecal specimens that did not contain culturable VRE. Passaging under antibiotic selection allowed us to isolate two species of anaerobic bacteria that were vans PCR positive, vancomycin resistant, and teicoplanin sensitive. Sequence analysis of the 16S rRNA genes showed that one isolate resembled Eggerthella lenta (98% identity), and the other Clostridium Innocuum (92% identity). Southern hybridisation and nucleotide sequencing showed a vane locus homologous to that in VRE. We propose that vans resistance in enterococci might arise hom gene transfer in the human bowel.