Genotypic diversity of Mycobacterium tuberculosis isolates and its association with drug-resistance status in Xinjiang, China

Xinjiang is a unique region of Central Asian part of China. It is widely noted for high tuberculosis burden and particularly for growing prevalence of drug resistance. Understanding genotypic distribution of Mycobacterium tuberculosis could help clarify unknown causes for the spread of drug-resistant strains. We analyzed 986 M. tuberculosis isolates collected from Xinjiang. Two genotyping schemes, i.e., spoligotyping and multiple-locus variable number tandem repeats (VNTR), were used to determine the phylogenetic lineages and their association with drug-resistances. The M. tuberculosis isolates studied displayed wide distribution of spoligotypic lineages, including Beijing, T, CAS, Ural, LAM, MANU, H, X, EAI, S, Microti, and BOV. The dominant Beijing lineage showed statistical difference from non-Beijing lineages in patients ages (P < 0.001), ethnic groups (P < 0.001) and resistance of three or more drugs (P = 0.008). Further analysis of the year of 2017 subset (n = 257) using VNTR scheme revealed an extremely high discrimination power (Hunter-Gaston discriminatory index = 0.9994). Cluster analysis showed a much lower recent transmission index (7.93%), indicating that the high drug-resistant tuberculosis in this region was mainly caused by reactivation or inappropriate therapy rather than by recent transmission. These data would be valuable for making and implementing policies for improving tuberculosis treatment and care in Xinjiang.