[Molecular epidemical characteristics of Mycobacterium tuberculosis strains from the nationwide random survey for the epidemiology of tuberculosis in China, 2000].

Objective: To explore the epidemical distribution characteristics of Mycobacterium tuberculosis isolated from China.

Methods: The M. tuberculosis strains were gained by multi-stratified grouping random sampling method from the nationwide random survey for the epidemiology of tuberculosis in China, 2000, and analyzed by IS6110-based RFLP and DR-based Spoligotyping DNA fingerprinting. These fingerprinting patterns were transferred into digital data and compared each other, and clustered by Gel compar4.1 Software. The clustering values in different TB patients were compared by chi(2) test and the risk factors for recent transmission were calculated by Odd Ratios.

Results: Two hundreds and four of 402 M. tuberculosis strains from this survey were determined to be "Beijing Genotype" M. Tuberculosis strain by DNA fingerprinting analysis. Three clusters M. tuberculosis strains sharing identical fingerprint pattern were found, including one cluster belong to a same family. There were significant difference between female and male, and younger (< 40 years old) and elder (>or= 40 years old) (P < 0.05). Odds Ratio 1 showed youth [1.68 95% CI (1.01 - 2.80)] and male [2.04 95% CI (1.07 - 3.96)], but Odds Ratio 2 showed youth [0.3 95% CI (0.2 - 0.44)] and male [4.96 95% CI (2.77 - 9.00)].

Conclusion: M. tuberculosis strains of Beijing Genotype are prevailing in China at present. Male and elder were shown to be significant risk factors for recent transmission. The infection source of M. tuberculosis could be traced by DNA fingerprinting.