Tuberculosis meningitis (TBM) is one of the most severe forms of tuberculosis. However, TBM diagnosis is quite challenging due to nonspecific clinical presentation and the paucity of the pathogen in cerebrospinal fluid (CSF) samples. In this study, we report a new method for detecting cell-free Mycobacterium tuberculosis DNA (cf-TB) in CSF and evaluate its clinical value for TBM diagnosis.
Of 68 patients prospectively recruited, 46 were diagnosed as having TBM and 22 as non-TBM. We compared the cf-TB method with CSF smear microscopy, mycobacterial culture, and the Xpert MTB/RIF assay (Xpert) using the consensus case definition for TBM proposed in 2009 as a reference standard.
The sensitivity of the cf-TB test was 56.5% (26/46) in patients with TBM, and it was significantly higher than other methods: microscopy (2.2%, 1/46; P < .001), mycobacterial culture (13.0%, 6/46; P < .001), and Xpert (23.9%, 11/46; P = .001). For specificity, none of the four methods reported false-positive results in the non-TBM group.
The new method detecting cell-free M tuberculosis DNA in CSF is rapid and accurate for diagnosis of TBM and easily incorporated into regular laboratory tests.