Genotypic Diversity Analysis of Mycobacterium tuberculosis Strains Collected from Beijing in 2009, Using Spoligotyping and VNTR Typing

BACKGROUND: Tuberculosis (TB) is a serious problem in China. While there have been some studies on the nationwide genotyping of Mycobacterium tuberculosis (M. tuberculosis), there has been little detailed research in Beijing, the capital of China, which has a huge population. Here, M. tuberculosis clinical strains collected in Beijing during 2009 were genotyped by classical methods. METHODOLOGY/PRINCIPAL FINDINGS: Our aim was to analyze the genetic diversity of M. tuberculosis strains within the Beijing metropolitan area. We characterized these strains using two standard methods, spoligotyping (n = 1585) and variable number of tandem repeat (VNTR) typing (n = 1053). We found that the most prominent genotype was Beijing family genotype. Other genotypes included the MANU, T and H families etc. Spoligotyping resulted in 137 type patterns, included 101 unclustered strains and 1484 strains clustered into 36 clusters. In VNTR typing analysis, we selected 12-locus (QUB-11b, MIRU10, Mtub21, MIRU 23, MIRU39, MIRU16, MIRU40, MIRU31, Mtub24, Mtub04, MIRU20, and QUB-4156c) and named it 12-locus (BJ) VNTR. VNTR resulted in 869 type patterns, included 796 unclustered strains and 257 strains clustered into 73 clusters. It has almost equal discriminatory power to the 24-locus VNTR. CONCLUSIONS/SIGNIFICANCE: Our study provides a detailed characterization of the genotypic diversity of M. tuberculosis in Beijing. Combining spoligotyping and VNTR typing to study the genotyping of M. tuberculosis gave superior results than when these techniques were used separately. Our results indicated that Beijing family strains were still the most prevalent M. tuberculosis in Beijing. Moreover, VNTR typing analyzing of M. tuberculosis strains in Beijing was successfully accomplished using 12-locus (BJ) VNTR. This method used for strains genotyping from the Beijing metropolitan area was comparable. This study will not only provide TB researchers with valuable information for related studies, but also provides guidance for the prevention and control of TB in Beijing.