Era of TB elimination: Growing need to understand diversities of Mycobacterium tuberculosis lineages!

Abstract

Introduction: The mycobacterium tuberculosis complex (MTBC) has highly clonal population structure which made the organism spread globally mirroring human migration out of Africa and resulted in the formation of seven lineages. We conducted this study to determine the proportion of spoligotype lineages and drug susceptibility profile of Mycobacterium tuberculosis isolates among smear positive TB patients attending a tertiary care hospital in Mysore, Karnataka, India.

Methods: It is a descriptive study conducted at JSS Hospital a tertiary care centre at Mysore, India during 2018-19. The sputum smear positive samples were subjected to solid culture and drug susceptibility testing and spoligotyping for identification of lineages.

Results: Of the 100 samples which were culture positive, 94 isolates were clustered into five spoligotype international types with SIT-126 (EAI-5) being the largest cluster of 46 (46%) isolates, followed by SIT-62 (H1) with 24 (24%), SIT -26 (CAS 1-DELHI) with 20 (20%), SIT-53 (T1) with 03 (3%) and SIT-482 (BOV-1) with 01 (1%). Among the remaining six isolates, two had unique Cameroon spoligotypes and four were orphans CONCLUSION: The study finding reveals that a diverse pattern of genotypes is circulating in the region of which EAI-5, Harleem (H1) and CAS-DELHI pattern forms the majority (88%). It is evident that there is a wide range of MTB genetic lineages in circulation and further research is needed to understand the diversity across the country.

Keywords: India; Lineages; Molecular epidemiology; Mycobacterium tuberculosis; Spoligotyping.