Genetic diversity of Mycobacterium tuberculosis isolates obtained from three distinct population groups in the Central Province, Sri Lanka

ObjectiveTo characterize the Mycobacterium tuberculosis (M. tuberculosis) isolates by spoligotyping and mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing to understand how M. tuberculosis strains transmit among the study population.MethodsSpoligotyping and MIRU-VNTR were used to genotype M. tuberculosis isolates obtained from three distinct population groups in Sri Lanka. General population suspected of having tuberculosis attending the Chest Clinic, Kandy (n = 78), patients having tuberculosis in Bogambara prison, Kandy (n = 22) and estate workers having tuberculosis in the Central Province, Sri Lanka (n = 50), from January 2012 to April 2014 were included in the study.ResultsAmong 150 isolates, a total of 19 distinct families were observed including 6 major spoligotyping-based families; East-African-Indian (39.33%), Haarlem (20%), Beijing (8.6%), Central European family T (6.5%), European family X (5.2%) and Central and Middle Eastern Asian (0.6%). Beijing strains were only identified among the general population. MANU strains were significant (36.36%) among the prisoners who had clustered with the MANU strains of the general population indicating contact cases and a possible transmission index within a particular geographical area. Haarlem 3 (34%) was the predominant strain among the estate workers. There was a close epidemiological relationship between the prisoners and the estate workers in the population.ConclusionsThe first insight of 15 loci MIRU-VNTR typing in conjunction with spoligotyping in a population in Sri Lanka demonstrated the feasibility and the applicability of these techniques to differentiate strains, their heterogeneity and the predominance of several worldwide distributed spoligotypes.