Genetic diversity and major spoligotype families of drug-resistant Mycobacterium tuberculosis clinical isolates from different regions of Turkey

To highlight the transmission rate and major phylogenetic clades of drug-resistant Mycobacterium tuberculosis isolates, a total of 200 drug-resistant strains isolated in four different regions of Turkey (Marmara n = 81; Mediterranean n = 39; Aegean n = 42; East Anatolia n = 38), were typed by spoligotyping and IS6110-restriction fragment length polymorphism (RFLP). The major spoligotyping-defined shared-types (STs) and corresponding lineages were, ST 41 (22.5%, LAM7-TUR), ST53 (19.5%, ill-defined T super-family), ST 50 (6.5%, Haarlem 3), ST 1261 (4.5%, LAM7-TUR), ST 47 (3.5%, Haarlem 1), as well as two STs that belonged to undefined clades (ST 284, 3%, and ST 2067, 2.5%). The global distribution of major M. tuberculosis lineages among drug-resistant strains was as follows: T super-family (29%), Latin-American & Mediterranean (33.5%), Haarlem (14%), and the S lineage (3%). A high number of strains (n = 29, 14.5%) showed patterns that did not fall within major clades described so far. A combination of spoligotyping and IS6110-RFLP fingerprinting methods resulted in a final clustering rate of 38.5% and a recent transmission rate of 25.5%. Our results underline the highly diverse nature of drug-resistant tuberculosis in our study population, as well as its ongoing transmission with lineages that are specific to these regions, the most predominant being the LAM7-TUR lineage which shows an enhanced phylogeographical specificity for Turkey.