MOLECULAR CHARACTERIZATION OF MYCOBACTERIUM TUBERCULOSIS STRAINS CIRCULATING IN THE URAL REGION, RUSSIA

Abstract. Overall 178 Mycobacterium tuberculosis isolates recovered in 2009–2011 from newly diagnosed epidemiologically unlinked to TB patients in the Ural region of Russia have been studied. The absolute concentration method was used for drug susceptibility testing. Mutations katG, inhA and rpoB associated with resistance to isoniazid and rifampicin were detected by microchip technology («TB-Biochip»). The isolates were genotyped by real-time PCR for the detection of Beijing/non-Beijing genotypes and 15-locus MIRU-VNTR typing according to «MIRU-VNTRplus» (http://www.miru-vntrplus.org). More than half (55.1%) of 178 isolates belonged to the Beijing family, 58.7% of them were multiple drug resistant (MDR) mostly due to rpoBSer531→Leu and katGSer315→Thr1 substitutions. Fifty VNTR profiles were found in 98 Beijing isolates; 57 of them grouped into 9 clusters. The largest VNTR cluster included 23 (23.5%) Beijing isolates and 21 of them were MDR. The 80 non-Beijing isolates showed 64 distinct VNTR patterns which belonged to 6 genetic families: LAM, Ural, Haarlem, etc. Among LAM and Ural isolates 30.4% and 28.6% were MDR, respectively. The 5 of 7 MDR LAM isolates had specific mutation profile:  rpoBAsp516→Val substitution and mutations katGSer315→Thr1 and inhA_T15. The MDR Ural isolates showed the heterogeneity of mutations in rpoB gene compared to other genotypes. Taken together, these findings suggest the emergence and spread of MDR-TB in the Ural region which is characterized by circulation of MDR strains of different genotypes with the Beijing family genotype to be predominant.