Characterization of Mycobacterium tuberculosis isolates from Hebei, China: genotypes and drug susceptibility phenotypes.

ABSTRACT

BACKGROUND: Tuberculosis remains a major public health problem in China. The Hebei province is located in the Beijing-Tianjin-Hebei integration region; however little information about the genetic diversity of Mycobacterium tuberculosis was available in this area. This study describes the first attempt to map the molecular epidemiology of MTB strains isolated from Hebei. METHODS: Spoligotyping and 15-locus MIRU-VNTR were performed in combination to yield specific genetic profiles of 1017 MTB strains isolated from ten cities in the Hebei province in China during 2014. Susceptibility testing to first line anti-TB drugs was also conducted for all strains using the L-J proportion method. RESULTS: Based on the SpolDB4.0 database, the predominant spoligotype belonged to the Beijing family (90.5%), followed by T family (6.3%). Using 15-locus MIRU-VNTR clustering analysis, 846 different patterns were identified, including 84 clusters (2-17 strains per cluster) and 764 individual types. Drug susceptibility pattern showed that 347 strains (34.1%) were resistant to at least one of the first line drugs, including 134 (13.2%) multi-drug resistance strains. Statistical analysis indicated that drug resistance was associated with treatment history. The Beijing family was associated with genetic clustering. However, no significant difference was observed between the Beijing and non-Beijing family in gender, age, treatment history and drug resistance. CONCLUSIONS: The Mycobacterium tuberculosis strains in Hebei exhibit high genetic diversity. The Beijing family is the most prevalent lineage in this area. Spoligotyping in combination with 15-locus MIRU-VNTR is a useful tool to study the molecular epidemiology of the MTB strains in Hebei.