Abstract

Objective: To determine tuberculosis epidemiology in Kandy, Sri Lanka. Methods: IS6110 RFLP and spoligotyping analyses were performed on 100 Mycobacterium tuberculosis (M. tuberculosis) clinical isolates from Kandy district, Sri Lanka. RFLP hybridization patterns (n=73) were analysed by the software GeneDirectory. Spoligotypes (n=1 1 0) were compared with the international database SPOTCLUST. Results: The majority of the circulating M. tuberculosis strains in Kandy belong to a single family, but the degree of IS6110 DNA polymorphism was high. 71 (80%) of the strains displayed distinct RFLP patterns and 63 (71%) were clustered into one main family. Within the family three isolates were grouped into one cluster while the rest isolates were grouped into one. The copy number varied from 1 to 17 while single copy strains were predominant (12) and 15 lacked the IS6110 element. Spoligotyping revealed a total of 24 families including the 9 major families. Strains were distributed among all the three principle genetic groups PGG1, PGG2, and PGG3. Except for two strains, the rest were not defined in the latest spoligotype database SpolDB4/ SITVIT. Conclusions: The first study of RFLP and spoligotyping of M. tuberculosis strains in Sri Lanka demonstrates the applicability of the genetic marker IS6110 to differentiate strains and the heterogeneity and predominance of several worldwide-distributed spoligotypes.

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