Utility of the Xpert MTB/RIF Assay for Diagnosis of Tuberculous Meningitis

摘要

Tuberculous meningitis (TBM) is characterized by copious cerebrospinal fluid (CSF) inflammation and yet few Mycobacterium tuberculosis. This combination creates a disease that is notoriously difficult to definitively diagnose. In this week's issue of PLOS Medicine, Patel and colleagues report the diagnostic performance of the GeneXpert system's Xpert MTB/RIF assay for the diagnosis of TBM in a cohort of 204 South African, predominantly HIV-infected, adults presenting with suspected meningitis of whom 59 had definitive TBM [1]. The Xpert MTB/RIF assay's overall sensitivity was 62%, and specificity was 95%. The performance was better using larger volumes of centrifuged CSF among HIV-infected persons with sensitivity of approximately 80% and excellent specificity for microbiologically confirmed TBM. Xpert MTB/RIF performance was less impressive using uncentrifuged CSF with a sensitivity of ≤50%, and Xpert MTB/RIF performance was negligible in HIV-uninfected persons.