Tuberculous meningitis in Bhubaneswar, Odisha, during 2016 to 2022

The burden of tuberculous meningitis varies substantially by location, and is influenced by the overall burden of tuberculosis in that geographical area, and the age structure of the population. Conventional methods for diagnosis of tuberculous meningitis include acid fast bacilli (AFB) smear and culture. AFB smear has low sensitivity and culture techniques are time consuming. During the last few years, rapid and sensitive molecular methods such as cartridge based nucleic acid amplification technique (CBNAAT) is being used for the diagnosis of tuberculous meningitis. In this study, we evaluated the burden of tuberculosis and rifampicin resistance in suspected cases of tuberculous meningitis in Bhubaneswar, Odisha, during February 2016 to December 2022 using CBNAAT.

Under the National Strategic Plan 2012-2017, CBNAAT machines were rolled out in 2016, of which 1 was installed in the National Reference Laboratory (NRL) for Tuberculosis in Bhubaneswar. For this study, retrospective data on CBNAAT testing of cerebrospinal fluid (CSF) samples at the NRL was collected and analyzed from February 2016 to December 2022. All the demographic and laboratory data were entered in Excel 2010 (Microsoft office, USA) for data analysis. The age and sex distribution of the presumptive TB patients, proportion of samples referred from public and private health care facilities, proportion of M. tuberculosis positive CSF samples along with sensitivity to rifampicin was evaluated. The study was approved by the Institutional Human Ethics Committee.

During February 2016 to December 2022, a total of 1627 CSF samples from presumptive TB meningitis patients were received in the NRL for CBNAAT testing. 60.7% (988/1627) of the presumptive TB patients were males. Of the 1627 patients, 3.1% (50/1627) were positive for M. Tuberculosis by CBNAAT. 56% (28/50) of the patients positive for tuberculous meningitis were males. The positivity for M. tuberculosis varied from 2.1% in 2017 to 5.1% in 2021. The CSF positivity for M. tuberculosis ranged from 0.7% in patients aged >60 years to 6.1% in 15-30 years age group. Of the 50 M. tuberculosis positive samples, 6% (3/50) were resistant for rifampicin.

Our study which included more than 1600 samples over a period of approximately 7 years found a 3.1% positivity for M. tuberculosis in CSF samples using CBNAAT. 6% of the M. tuberculosis positive samples were resistant to rifampicin. Future studies involving data from other districts of Odisha will help provide a more accurate information on the prevalence of tuberculous meningitis in Odisha state.