OBJECTIVETo explore the characteristics on molecular epidemiology of Mycobacterium tuberculosis isolates from hospitals in Tianjin area.

METHODSOne hundred M. tuberculosis isolated strains were collected in succession from August 16th-December 25th, 2005 in Tianjin Haihe Hospital and genotyped by spoligotyping and multiple locus variable number-tandem repeat(VNTR). Data was analyzed by cluster software. Based on the concept of Beijing lineage, it was determinate two sub-groups: atypical Beijing strains and W strain/typical family strains by multiplex and real-time PCR. The associations of subgroups with drug resistance and age were assessed by the chi2 test.

RESULTS96 M. tuberculosis strains were genotyped in which 91.7% (88/96) strains belonged to Beijing genotype (including 3 Beijing-like strains) by spoligtyping. VNTR typing could differentiate 60 genotypes among the 88 Beijing genotype strains. 93.2% of the Beijing lineage M. tuberculosis strains of this study belonged to W strain/typical Beijing family strains (82/88). No statistically significant differences were observed in the proportions of the two sub-groups in patients of different age, or drug resistance (P > 0.05).

CONCLUSIONThe M. tuberculosis Beijing genotype strains were dominated on tuberculosis hospital patients of Tianjin area. The discriminatory power of VNTR typing was higher than that of spoligtyping. The two sub-groups of Beijing lineage had been prevalent in Tianjin, however W strain/typical Beijing family strains were of preponderance.