Comparative Evaluation of GeneXpert MTB/RIF Assay and Microscopy for Rapid Diagnosis of Tuberculous Meningitis in Children

Tuberculous meningitis (TBM) is the most devastating complication of Mycobacterium tuberculosis infection. Diagnosis of TBM is challenging in young children due to the paucibacillary nature of disease. Microscopy for acid-fast bacilli in CSF is fast but has very low sensitivity whereas culture may take up to 42 days. Due to the urgency of diagnosis in suspected TBM cases, a rapid, accurate diagnostic test could have a great impact on survival. Aims of the study are to prospectively determine the diagnostic accuracy of Xpert MTB/RIF in a large consecutive series of samples from patients presenting with suspected Tuberculous meningitis. In this prospective hospital-based study, 147 children presenting with suspected tuberculous meningitis from May 2017 to February 2018 were included. Cerebrospinal fluid samples were tested by Ziehl-Neelsen smear, mycobacterial culture on Lowenstein Jensen medium, and Xpert MTB/RIF assay. Kappa statistics (K) was used to determine agreement beyond what would be expected by chance between smear microscopy and Gene Xpert assay results. Out of a total of 147 CSF samples tested, 10 (6.8%) were positive for Mycobacterium tuberculosis by Xpert MTB/RIF assay. Out of these 10 samples, only one showed AFB on ZN smear. Culture was negative for all the 147 CSF samples. The MTB/RIF test has a short turnaround time and simultaneously detects M. tuberculosis and RIF resistance in less than 2h. It could be a useful tool for rapid identification of M. tuberculosis, especially in smear-negative clinical samples.