Characterization of Mycobacterium tuberculosis isolates from Shijiazhuang, China: genotypes and drug resistance

To understand the genetic diversity and phenotypic resistance of Mycobacterium tuberculosis (MTB) strains isolated in Shijiazhuang. Spoligotyping and MIRU-VNTR were performed to genotype MTB isolates and drug susceptibility testing (DST) was used to obtain phenotypic resistance. The genotyping result with drug resistance profiles and clinical characteristics was assessed. A total of 422 strains were collected from Shijiazhuang. The predominant lineage was the Beijing family (91.0%). The VNTR-15standard divided 69 strains into 27 clusters (2-7 strains per cluster) and 353 individual types. The clustering rate was 9.95% and HGDI value reached 0.999. In contrast, the VNTR-15China with a clustering rate of 40.3% and a HGDI score of 0.989, grouped 229 strains into 59 clusters (2-32 strains per cluster) and 193 unique genotypes. MTB drug resistance rate in retreatment patients was statistically higher than that of initial treatment panels. However, no statistical difference of drug resistance rate was observed between the Beijing and the non-Beijing genotypes. The Beijing family is the predominant genotype in Shijiazhuang. Anti-TB drug treatment is associated with MTB drug resistance. VNTR-15standard has a higher discriminatory power than VNTR-15China. Combination of spoligotyping and MIRU-VNTR is suitable for understanding the molecular epidemiology of MTB strains in Shijiazhuang.