Performance of the GeneXpert® enterovirus assay for detection of enteroviral RNA in cerebrospinal fluid

BackgroundThe GeneXpert® Dx System allows for automated extraction, processing, amplification and real-time detection of target nucleic acids.ObjectivesTo evaluate the performance of the Cepheid Xpert™ enterovirus (EV) assay for detection of EV RNA compared to a nucleic acid sequence based amplification (NASBA®) assay and a user-developed TaqMan® RT-PCR assay.Study designAssays were evaluated using a 12-member proficiency panel and up to 138 CSF specimens. Samples in which EV RNA was detected by two or more assays were considered true positives.ResultsThe GeneXpert, NASBA, and TaqMan assays correctly identified 10, 8, and 7 of 12 proficiency panel members, respectively. For detection of EV RNA in CSF, the sensitivities of the GeneXpert, NASBA, and TaqMan were 100%, 87.5%, and 96%, respectively. There were no false positives. Two samples tested by GeneXpert and NASBA yielded indeterminate or invalid results and could not be resolved.ConclusionsThe Xpert EV assay is a sensitive and specific method for detection of EV RNA in CSF specimens. The ease of use, random access capability, and minimal hands-on time with the automated GeneXpert system affords laboratories with little molecular diagnostics expertise an opportunity to complete a clinically useful testing within 2.5 h.