Genotypic characteristics of Mycobacterium tuberculosis circulating in Xinjiang, China

Background: Tuberculosis (TB), a chronic infectious disease caused by Mycobacterium tuberculosis (MTB), poses a serious threat to human health. We investigated the genotypes of MTB in the high prevalence province Xinjiang, China. Methods: From March 2010 to May 2013, 381 MTB isolates from patients with pulmonary TB were analyzed by molecular typing of 24 mycobacterial interspersed repetitive unit-variable number tandem repeat loci and PCR detection of the deleted regions of difference of the Beijing/W lineage and its sublineages. Results: These isolates were shown to be highly polymorphic and to be composed of 345 unique genotypes, including 30 genotype clusters consisting of 2 or 3 strains and 315 individual genotypes. The genotype clustering rate was 17.32% and recent transmission index was low (9.45%). The Beijing/W lineage strains accounted for 57.48% of the isolates, and this predominant family strain was further subdivided into four sublineages: 181 (69.86%), 207 (14.61%), 105 (10.96%), and 150 (4.56%). Conclusions: The Beijing/W lineage (especially sublineage 181) strains were predominant and were associated with the transmissibility of TB in Xinjiang. Based on our data, we hypothesize that the circulating MTB strains in Xinjiang have significant genetic diversity and that the majority of the TB in Xinjiang may be explained by non-recent transmission emerging by endogenous reactivation. The possibility of outbreak is low, and current measures to control TB should first focus on standardized treatment of TB patients to prevent reactivation of latent infections.