Distribution and association of Mycobacterium tuberculosis CAS lineage with multidrug resistance in North India.

SETTING: A tertiary care hospital in North India.

OBJECTIVES: To determine the prevalence of different genotypes and examine their association with drug resistance among clinical isolates of Mycobacterium tuberculosis from the northern region of India.

DESIGN: We analysed 100 clinical isolates of M. tuberculosis using mycobacterial interspersed repetitive units genotyping and TbD1 analysis.

RESULTS: The analysis revealed that 34% of strains belonged to the Delhi/CAS (TbD1-) lineage, 32% had unknown patterns (27 TbD1-, 5 TbD1+), 18% were of Beijing genotype (TbD1-) and 11% were of EAI lineages (TbD1+). Twenty-one strains were multidrug-resistant tuberculosis (MDR-TB), 9 of which belonged to the Delhi/CAS lineage, 4 were of Beijing lineage, 6 were of unknown pattern and one was of EAI lineage. Our meta-analysis showed the overall proportion of CAS lineage to be 42.96% (95%CI 33-52); the CAS lineage had no association with MDR-TB (OR 0.89, 95%CI 0.66-1.20).

CONCLUSION: The study highlights the high proportion of CAS lineage strains and absence of association with MDR-TB. The distribution and identification of different genotypes of M. tuberculosis could help in better understanding the factors that influence disease transmission and drug resistance.