[The cluster and drug-resistant characteristics of Beijing genotype Mycobacterium tuberculosis in eastern rural China].

OBJECTIVE

To investigate the distribution of Mycobacterium tuberculosis (MTB) Beijing genotype, which was isolated from tuberculosis (TB) patients registered in local TB dispensaries in Deqing and Guanyun county respectively within 1 year, as well as its drug-resistant phenotypic and genotypic profiles and genotyping features.

METHODS

A total of 399 TB patients were enrolled from 2 counties. Of the 351 TB patients with MTB isolates available, 237 were male, and 114 were female; aged from 18 - 82 (46 ± 35) years. The proportion method and DNA sequencing were used to define the susceptibility of the isolates to 4 first line anti-TB drugs and the related mutation. Beijing genotype MTB strains were identified by Spoligotyping, while the "cluster" strains and the "unique" strains were defined by IS6110 restriction fragment length polymorphism (RFLP).

RESULTS

Beijing genotype MTB strains were identified in 243 of the 351 strains isolated, and the proportion of multi-drug resistance, mono-resistance to rifampin and isoniazid among Beijing genotype MTB was 18.5% (45/243), 43.2% (105/243) and 22.2% (54/243) respectively, all being significantly higher than the non-Beijing genotype MTB, 7.4% (8/108), 24.1% (26/108) and 12.0% (13/108) respectively. katG and rpoB mutations were observed more common among Beijing genotype MTB than among non-Beijing genotype MTB, 13.2% (32/243) and 4.6% (5/108) respectively, OR = 2.553, 95%CI: 1.031 - 6.324. The Beijing genotype MTB was more likely to be clustered than non-Beijing genotype MTB, 41.2% (100/243) and 11.1% (12/108) respectively, OR = 5.503, 95%CI: 2.851 - 10.622.

CONCLUSIONS

In eastern rural China, TB patients infected with the Beijing genotype MTB may have a higher risk to develop isoniazid-or rifampin-resistance and multi-drug resistance. The disease is more likely due to recent transmission.