Role of Cartridge Based Nucleic Acid Amplification Test of Cerebrospinal Fluid in the Diagnosis of Tubercular Meningitis

Abstract

Introduction: Tubercular meningitis is the commonest form of neurotuberculosis. Diagnosis is challenging because of paucibacillary nature, lack of specific sign and symptoms. CBNAAT is a real time Polymerase Chain Reaction (PCR) test for the diagnosis of tubercular meningitis. So we used this rapid test to assess its role in diagnosis of Tubercular Meningitis(TBM). Material and Methods: This study was done over a period of one year in a tertiary centre. Patients with symptoms suggestive of tubercular meningitis were our study population. Their detailed clinical history, followed by a thorough general physical & systemic examination were done and documented in a predesigned proforma. Chest x-ray as well as neuroimaging were done in patients whose condition permitted. 3ml CSF fluid was drawn by lumbar puncture, 2 ml was sent for routine and bacteriological examination test and 1 ml for CBNAAT. Results: 100 patients were included, with a male to female ratio of 1.7:1. Mean age of the affected population was 37.53 years. 47% had radiological finding suggestive of tuberculosis.18 out of 100 were HIV reactive. MRI brain in 64 patients showed meningeal enhancement as the most common finding (60.93%). In Cerebrospinal Fluid (CSF) analysis mean CSF protein was 136.5 mg/dl, mean CSF glucose was 56.4 mg/dl and CSF cell count was 66.7 cells/microliter. Mean Adenosine Deaminase (ADA) was 11.22 U/L.CSF CBNAAT was positive in 9 patients out of which 8 were sensitive to rifampicin and one resistant to it. Conclusion: Even though CSF cytology gives good estimate of suspected TBM patient the test is not confirmative for bacilli demonstration. CBNAAT being a rapid accurate test would play a major role in the diagnosis, treatment, as well as for estimating rifampicin resistance of one of the common medical emergency in India by clear guidance from WHO.