Genotypic characterisation of Mycobacterium tuberculosis isolates from tuberculous meningitis patients at a tertiary neurocare centre in Southern India

Aims: Specific genotypes of Mycobacterium tuberculosis (MTB) have been reported to cause outbreaks of pulmonary tuberculosis (TB) in geographical areas that are endemic to TB. However, since there is little epidemiological evidence on the association of particular genotypes that cause tuberculous meningitis (TBM), we sought to investigate the association of specific MTB strains with infection of the central nervous system (CNS). Materials and Methods: We carried out a genetic characterisation of 89 MTB isolates from TBM patients at a Southern Indian tertiary neurocare centre and compared the genotypes with strains of pulmonary TB isolated from Indian immigrants in New York City. We applied the standard methods of genotyping of MTB, namely, IS6110-based restriction fragment length polymorphism and spoligotyping for strain identification, along with principal genetic grouping and single-nucleotide polymorphism cluster analysis. Results: The analysis revealed a high-level of diversity amongst the strain population. The genotypes of the isolates from TBM patients paralleled the pulmonary TB strain population recovered from the Indian immigrants in NYC. Conclusions: We conclude that there is no apparent association between genotypes of MTB and propensity to infect CNS tissue.