黑龙江省五常市结核分枝杆菌基因型及传播特征

Genotypic and transmission characteristics of Mycobacterium tuberculosis in Wuchang City, Heilongjiang Province

目的根据黑龙江省结核分枝杆菌差异区域105(RD105)缺失基因检测与北京基因型菌株的相关性分析,了解黑龙江省五常市结核分枝杆菌基因型特征及传播特征,为该地区控制结核病提供有效的工具。方法对黑龙江省五常市结核病防治(简称“结防”)所登记并培养阳性的121例肺结核患者的结核分枝杆菌分离株,采用比例法药敏试验检测其耐药性,用RD105缺失基因检测和7个位点可变数目串联重复序列(variable number of tandem repeats,VNTR)进行分子分型,计算耐药率、Hunter-Gaston指数(Hunter-Gaston Index,HGI)、成簇率,分析结核分枝杆菌DNA多态性及北京基因型菌株与耐药的相关性。结果在黑龙江省五常市121株结核分枝杆菌菌株中,通过RD105缺失基因检测,其结果显示有101株为北京基因型菌株,占83.5%.(101/121),其余20株为非北京基因型菌株,占16.5%(20/121)。121株菌株对异烟肼、利福平、乙胺丁醇、链霉素的耐药率分别为5.8%(7/121)、3.3%(4/121)、5.0%(6/121)、15.7%(19/121);其中北京基因型菌株对上述药物的耐药率分别为5.0%(5/101)、3.0%(3/101)、5.9%(6/101)、17.8%(18/101),非北京基因型菌株对上述药物的耐药率分别为10.0%(2/20)、5.0%(1/20)、5.0%(1/20)、未检出对乙胺丁醇耐药0.0%(0/20)。两者比较差异无统计学意义(χ2=1.090,P=0.296)。121株菌株中耐多药率为2.5%(3/121),其中2株为北京家族基因型,1株为非北京基因型;北京基因型和非北京基因型耐多药率分别为2.0%(2/101)和5.0%(1/20),两者比较差异无统计学意义(χ2=0.531,P=0.460)。进一步使用7位点VNTR分型技术检测,结果显示121株菌株可分为17个基因簇和64个独立的基因型;每个簇包括2~14株临床分离株,最大的簇由14株结核分枝杆菌菌株构成,所占比较高为11.6%(14/121);121株结核分枝杆菌菌株中成簇菌株57株,成簇率为47.1%(57/121)。近期感染率最小估计值为33.1%(40/121)。7位点VNTR检测结果表现出高度多态性,各位点的HGI值为0.513~0.786;经聚类分析,121株结核分枝杆菌菌株可分为3个大的基因群(Ⅰ群、Ⅱ群、Ⅲ群),81个基因型。分别为:Ⅰ群占14.9%(18/121),含15个基因型;Ⅱ群占76.9%(93/121),含59个基因型,Ⅲ群占8.2%(10/121),含7个基因型。结论北京基因型为黑龙江省五常市主要流行株,且该地区的结核分枝杆菌呈明显的基因多态性。耐药菌株中北京基因型菌株所占比率较高,要加强对耐药优势菌群的监测和防控。

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.