Cerebrospinal fluid Gene XPERT (CBNAAT) in children with tuberculous meningitis

To observe the role of CSF Gene XPERT (CBNAAT) in diagnosis of tuberculous meningitis (TBM) and determine its sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

A prospective study was done from October 2017 to March 2020. CSF samples of 55 children diagnosed as tuberculous meningitis as per defined clinical and imaging criteria, were subjected to routine CSF analysis, MGIT culture and CBNAAT. Children on prior anti-tuberculous therapy for more than one month were excluded from study.

Of 55 children, meningeal signs were present in 54.5% children. Neurological deficits were present in 47.3%. Common CT brain findings were communicating hydrocephalus followed by infarct and basal exudates. CSF Gene XPERT (CBNAAT) were positive in 9 (16.4%), of which 6 was also culture positive and 3; negative. Two children were rifampicin resistant. Fifteen (27.3%) children had positive CSF culture. Gene XPERT showed sensitivity, specificity, PPV, NPV and diagnostic accuracy of 40%, 92.5%, 66.7%, 80.4% and 78.2% respectively as compared to culture.

Although sensitivity of CSF CBNAAT is low i.e. 40% but positive result not only confirm bacteriological diagnosis of tuberculous meningitis but also reveal about rifampicin sensitivity and resistance for plan of therapy.