Abstract:

Objective According to the correlation analysis between the differential gene detection of Mycobacterium tuberculosis 105 (RD105) and Beijing genotype strains in Heilongjiang Province, the genotypic and transmission characteristics of Mycobacterium tuberculosis in Wuchang City, Heilongjiang Province were analyzed, which provided effective control tools for tuberculosis in the region.Methods The Mycobacterium tuberculosis isolates from 121 patients with pulmonary tuberculosis who were registered and cultured positively in the tuberculosis control of Wuchang City, Heilongjiang Province (referred to as “TB prevention”) were tested for drug susceptibility testing by proportional susceptibility test, using RD105 deletion gene test and 7 Molecular typing of variable number of tandem repeats (VNTR), calculation of drug resistance rate, Hunter-Gaston index (HGI), clustering rate, ana-lysis of Mycobacterium tuberculosis DNA polymorphism and the correlation between Beijing genotype strains and drug resistance.Results In 121 strains of Mycobacterium tuberculosis in Wuchang City, Heilongjiang Province, the RD105 deletion gene was detected. The results showed that 101 strains were Beijing genotype strains, accounting for 83.5% (101/121), and the remaining 20 strains were non-Beijing genotype strains accounting for 16.5% (20/121). The resistance rates of 121 strains to isoniazid, rifampicin, ethambutol and streptomycin were 5.8% (7/121), 3.3% (4/121), 5.0% (6/121) and 15.7% (19/121), respectively. The resistance rates to the above four drugs were 5.0% (5/101), 3.0% (3/101), 5.9% (6/101) and 17.8% (18/101) in Beijing genotype strains, and were 10.0% (2/20), 5.0% (1/20), 5.0% (1/20), and 0.0% (0/20) in non-Beijing genotype strains. There was no significant difference about drug resistance rates between the Beijing type strains and non-Beijing type strains (χ ²=1.090, P=0.296). The resistance rate of 121 strains was 2.5% (3/121), of which 2 were Beijing family genotypes, 1 was non-Beijing genotypes. Beijing genotypes and non-Beijing genotypes were 2.0% (2/101) and 5.0% (1/20), respectively without significant difference statistically (χ ²=0.531, P=0.460). Further, using 7-site VNTR typing technology, the results showed that 121 strains can be divided into 17 gene clusters and 64 independent genotypes; each cluster includes 2-4 clinical isolates, and the largest cluster consists of 14 strains of tuberculosis. The composition of mycobacterial strains was 11.6% (14/121); the clusters of 57 strains of M.tuberculosis strains were 57, and the clustering rate was 47.1% (57/121). The minimum estimated infection rate is 33.1% (40/121). The 7-site VNTR test results showed a high degree of polymorphism, and the HGI values of each point were 0.513-0.786. According to the cluster analysis, 121 strains of M.tuberculosis strains can be divided into three large gene groups (Ⅰ group, Ⅱ group and group Ⅲ) and 81 genotypes. They were group Ⅰ accounted for 14.9% (18/121, including 15 genotypes), group Ⅱ accounted for 76.9% (93/121, including 59 genotypes), group Ⅲ accounted for 8.2% (10/121, including 7 genotypes).Conclusion The Beijing genotype is the main epidemic strain in Wuchang City, Heilongjiang Province, and the Mycobacterium tuberculosis in this area shows obvious genetic polymorphism. Among the drug-resistant strains, the Beijing genotype strains account for a relatively high proportion, and it is necessary to strengthen the monitoring and prevention of the dominant drug-resistant flora.

Key words: Mycobacterium tuberculosis, Sequence tagged sites, Tandem repeat sequences, Tuberculosis, multidrug-resistant, Genotype, Epidemiologic study characteristics as topic