Efficiency of the Cepheid Xpert vanA/vanB assay for screening of colonization with vancomycin-resistant enterococci during hospital outbreak

This study aimed to assess the efficiency of the Cepheid Xpert vanA/vanB test for detecting vancomycin-resistant enterococci (VRE) colonization during a VanA Enterococcus faecium outbreak and to compare the Cepheid Xpert vanA/vanB (Cepheid, Sunnyvale, USA) test to a culture method with chromogenic medium chromID VRE agar (bioMérieux). The Cepheid Xpert vanA/vanB assay showed sensitivity 61.5%, specificity 79.2%, positive predictive value 61.5% and negative predictive value 79.2%. The results obtained in this study demonstrate that a positive result in the Cepheid Xpert vanA/vanB test for vanA enables the rapid (less than 1 h) presumptive, prior to culture, recognition of patients colonized with VRE. However, the Cepheid Xpert vanA/vanB assay cannot be the only test used to screen patients during an ongoing VRE outbreak, because additional culturing of all samples negative for both vanA and vanB or positive for vanB should be performed in order to confirm the carrier status of the patient.