title: Screening for vancomycin-resistant enterococci with Xpert®vanA/vanB: diagnostic accuracy and impact on infection control decision making.
abstract: Vancomycin-resistant enterococci (VRE) are increasingly important nosocomial pathogens and screening for colonization status is a mainstay in infection control. We implemented PCR-based screening duringvanA-positiveEnterococcus faeciumoutbreaks in four university hospitals in Copenhagen, Denmark. Xpert®vanA/vanBwas performed directly on rectal swabs and thevanAPCR result was used to guide infection control measures. Concurrently, all samples were selectively cultured including an overnight enrichment step. Diagnostic accuracy was calculated as well as turnaround time and the impact of the earlier available PCR results on infection control decision making. In all, 1110 samples were analysed. ThevanAPCR positivity rate was 13.8% and culture positivity rate was 15.2%. The diagnostic accuracy of thevanApart of the assay was high with a sensitivity of 87.1%, a specificity of 99.7%, and positive and negative predictive values of 98.0% and 97.7%, respectively. ThevanBPCR had a considerably lower specificity of 77.6% and a positive predictive value of 0.4%. In 1067 (96.1%) samples, PCR results were reported within 1 day, whereas median culture turnaround time was 3 days. The saving of time to available results corresponded to 141 saved isolation days and 292 saved transmission risk days. False-negative or false-positive PCR results led to six additional transmission risk days and 13 additional isolation days, respectively. ThevanAPCR had high diagnostic accuracy and the prompt availability of results gave a considerable benefit for infection control decision making.
authors.affiliation: Department of Clinical Microbiology, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark.
authors.forename: B J
authors.initials: BJ
authors.lastname: Holzknecht
authors.affiliation: Department of Clinical Microbiology, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark.
authors.forename: D S
authors.initials: DS
authors.lastname: Hansen
authors.affiliation: Department of Clinical Microbiology, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Nielsen
authors.affiliation: Department of Clinical Microbiology, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Kailow
authors.affiliation: Department of Clinical Microbiology, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark.
authors.forename: J O
authors.initials: JO
authors.lastname: Jarløv
keywords: Infection control; PCR-based screening; molecular screening; selective culture; vanA; vancomycin-resistant enterococci