Sequential Testing with Xpert MTB/RIF assay for Diagnosis of Tuberculous Meningitis in Maharaj Nakorn Chiang Mai University Hospital

Abstract

Early diagnosis and appropriate treatment are crucial in the effort to reduce morbidity and mortality from tuberculous meningitis (TBM). This cross-sectional study aimed to investigate the diagnostic performance of the Xpert MTB/RIF assay in accurately diagnosing TBM. Sixty-five CSF specimens from patients at Maharaj Nakorn Chiang Mai University Hospital, Thailand, who had subacute lymphocytic meningitis between January 2015 and March 2016 were included for analysis. By using Mycobacteria growth indicator tube (MGIT) culture as a reference standard, the sensitivity and specificity of the Xpert MTB/RIF assay were 83.33% (95% CI 57.19–98.22) and 96.23% (95% CI 87.02–99.54), respectively. There was good agreement between the Xpert MTB/RIF assay and MGIT culture of 93.85% (p < 0.001) and a kappa score of 0.796 (95% CI 0.603–0.988). By using a TBM score as a cut-off point of 6, followed by the Xpert MTB/RIF assay as the sequential testing, there was an improvement in specificity from 96.23–97.15%. This study demonstrated that the Xpert MTB/RIF assay was a fast and accurate method for detecting M. tuberculosis from centrifuged CSF specimens, with a high level of sensitivity and specificity. The diagnostic algorithm of sequential testing, combined with the TBM scoring system and the Xpert MTB/RIF assay, could improve diagnostic performance.