Molecular snapshot of Mycobacterium tuberculosis population in Kazakhstan: a country-wide study

Republic of Kazakhstan is among the 27 high multidrug-resistant tuberculosis (MDR-TB) burden countries in the world. Here, we analyzed the population structure and phylogeography of Mycobacterium tuberculosis in Kazakhstan and impact of the identified genotypes on spread of drug resistant strains. A total of 159 M. tuberculosis isolates from different regions of Kazakhstan were typed using 24-MIRU-VNTR and spoligotyping, and the profiles were compared to the MIRU-VNTRplus and SITVIT_WEB databases. Eight isolates with double VNTR alleles were excluded from further analysis that was performed on 151 isolates. They were assigned to 10 families, Beijing (n = 109) being the largest and dominated by a single clonal cluster 94-32 and derived profiles (n = 101). The other families were represented mainly by LAM (n = 17), Ural (n = 8), NEW-1 (n = 3) and a new cluster named KAZ-1 (n = 8). Beijing, LAM and Ural isolates were detected in all parts of the country while Iran-specific family NEW-1 was found only in southern Kazakhstan (P = 0.001). A reduced scheme of 10 most polymorphic VNTR loci provided a discrimination similar to that achieved by 15-MIRU scheme and may be recommended for rapid preliminary screening of the clinical isolates in Kazakhstan. Multi-drug resistance was significantly more prevalent among Beijing (64/109) and LAM (7/17) strains compared to strains of other families (1/25; P = 0.0006 and 0.01, respectively). High prevalence of the genetically closely related MDR strains of the Beijing genotype found in different regions of Kazakhstan highlights their crucial impact on the current TB epidemic in this country.