Comparison of direct cultivation on a selective solid medium, polymerase chain reaction from an enrichment broth, and the BD GeneOhm™ VanR Assay for identification of vancomycin-resistant enterococci in screening specimens

Abstract

Fast and reliable diagnostics of vancomycin-resistant enterococci (VRE) is an important prerequisite for containing VRE transmission rates and controlling VRE outbreaks among hospital patients. The BD GeneOhm™ VanR Assay (Becton Dickinson Diagnostics, Erembodegem, Belgium) is a real-time polymerase chain reaction (PCR) assay for screening perianal/rectal samples for the presence of vanA or vanB genes that can be associated with VRE. A set of 51 reference strains (vanA–G genotypes) were correctly identified. Performance of the assay was evaluated and compared with culture-based methods and subsequent PCR analysis in 2 university hospitals with a different VRE prevalence. A total of 1786 samples were analyzed. With the use of the BD GeneOhm™ VanR Assay, 88 of 102 vanA-positive specimens, 62 of 67 vanB-positive specimens, 3 of 4 vanA- and vanB-positive specimens, and 1403 of 1613 negative specimens were correctly identified. The overall sensitivity was 93.1%; the specificity was 87.0% mainly due to false-positive vanB results. Results did not differ between study institutions.