Abstract: Objective To study the genotypic constitution of M. tuberculosis isolates from Inner Mongolia, and the distribution characteristics of “Beijing family” strains in this area.   Methods 372 M. tuberculosis clinical strains isolated from confirmed patients with tuberculosis in 2011, including the patients’epidemiological and clinical information, were collected from Institute for Tuberculosis Control and Prevention, Inner Mongolia and were genotyped by traditional 43 space Spoligotyping. The results of the DNA fingerprinting of these 372 strains were analyzed with BioNumerics 5.0 software, and compared with SpolDB 4.0 database. In addition, NTF and LSP were used to explore the characteristics of the “Beijing family” strains. Among these strains, 282 were from the patients of Han, 84 were from the patients of Mongolian, the rest including 4 strains, 1 strain and 1 strain were from Hui, Uygur and Manchu respectively. The relativity between the susceptibility of the Beijing genotype and the two major nationalities was analyzed. The statistical analyses were performed by the software of the SPSS 13.0, and the chi-square test was used to determine the susceptibility of the Beijing genotype in the two major nationalities (Mongolian and Han).   Results 372 strains were divided into 48 genotypes by spoligotyping referring to SpolDB 4.0 database. According to the database, 24 genotypes were new types. “Beijing family” genotype was the most prevalent genotype (85.48%, 318/372), followed by the T family (4.84%, 18/372), H family (0.81%, 3/372), MANU family (0.27%, 1/372) and Latin American and Mediterranean family (0.27%, 1/372). Among these strains of the Han patients, 87.94%(248/282) were “Beijing family”, and 12.06% (34/282) were non-“Beijing family”. Meanwhile, there were 79.76%(67/84) “Beijing family” strains and 20.24% (17/84) non-“Beijing family” strains in the Mongolian. Finally, the chi-square test between susceptibility of the “Beijing family” genotype and the two major natio-nalities (Mongolian and Han) showed that there was no statistical significance (χ²=3.612, P=0.057).   Conclusion There are genotypic diversities of M. tuberculosis clinical strains, and “Beijing family” genotype is the most prevalent family in Inner Mongolia. We did not find any relevance between the “Beijing family” genotype and the major nationalities.

Key words: Mycobacterium tuberculosis, Genotype, Bacterial typing techniques, Molecular typing, Polymorphism, genetic, Epidemiology, molecular, Inner mongolia, Han nationality