Multidrug-Resistant Tuberculosis Strains with Ethnic Diversity in the Republic of Buryatia

Buryatia is a region with a high incidence of multidrug-resistant tuberculosis (MDR- TB) and an ethnically diverse population (30% of Mongoloid Buryats and 65% of Russians). We have analyzed M. tuberculosis strains isolated from newly diagnosed patients. Beijing genotype was more prevalent among Russians than among Buryats (68% vs. 53%; P = 0.055). European non-Beijing genotypes (LAM, Ural, Haarlem) were twice more prevalent in Buryats than in Russians (39.2% vs. 20.5%; P = 0.01). The higher prevalence of Beijing genotype among former prisoners (79% vs. 61% in other patients, P = 0.1) indicates its increased contagiousness. Russian epidemic cluster B0/W148 accounted for 9.5% of cases, half that in other regions of Siberia. Hypervirulent Beijing 14717- 15 cluster was endemic in Buryatia and had been isolated more frequently among Russians than among Buryats (9.1% vs. 3.9%; P = 0.2). Beijing B0/W148, CAO, and 14717-15 subtypes were associated with multidrug resistance (P = 0.01–0.0001). HIV coinfection was more common for Russians than for Buryats: 35/141 (24.8%) vs. 5/51 (9.8%), P = 0.03. It is concluded, that M. tuberculosis population structure in Buryatia has retained its characteristics compared to other regions of Russia and differs significantly from neighboring Mongolia. The circulation of Beijing subtypes associated with pronounced MDR and drug-resistant non-Beijing strains shows the risk of their wider dissemination.