宜昌地区结核分枝杆菌基因分型与成簇特征分析

目的 描述宜昌地区结核分枝杆菌的基因分型及成簇特征,为宜昌地区的结核病防治提供依据。方法 搜集宜昌地区2016年12月至2017年5月经基因芯片检测阳性的结核病患者痰标本,接种罗氏培养基进行培养后,得到的367株结核分枝杆菌临床分离株选择国际通用的24位点结核分枝杆菌散在分布重复单位及可变数目串联重复序列(MIRU-VNTR)进行分子分型,用Hunter-Gaston指数(HGI)和遗传差异值(h)对MIRU位点的分辨率和差异性进行评价;运用BioNumerics 5.0软件对VNTR-MIRU结果进行成簇性分析,根据近期传播率公式计算其近期传播率;367株菌株分离来自367例患者,细分为初治患者321例、复治患者46例后分别进行成簇率统计,初复治患者的成簇率比较采用χ ²检验,P<0.05为差异有统计学意义。结果 367株结核分枝杆菌24位点VNTR-MIRU分型结果显示,其总的分辨率HGI值为0.999,其中遗传多样性最高的位点为QUB11b,其h值为0.79;遗传多样性最低的位点为MIRU24,其h值为0.03。分析时发现基因型呈明显的多态性,总共有324个基因型。成簇性分析发现,其中90株菌株形成39个簇,成簇率为24.52%(90/367),近期传播率为13.90%(51/367);复治患者菌株成簇率为21.74%(10/46),初治患者菌株成簇率为24.92%(80/321),两者成簇率比较,差异无统计学意义(χ ²=0.220,P=0.639)。结论 宜昌地区的结核分枝杆菌呈现出较高的遗传多样性,近期传播率较低,且成簇率与初复治无关,提示宜昌地区结核分枝杆菌以内燃复发为主,也存在小范围内的流行,在结核防控方面要加以重视。

MIRU-VNTR genotyping and clustering of Mycobacterium tuberculosis isolates in Yichang

Objective To determine the genotypes and clustering patterns of Mycobacterium tuberculosis in Yichang and provide evidence for use in the prevention and treatment of tuberculosis.Methods Sputum samples determined to be positive for Mycobacterium tuberculosis using gene microarrays were collected in Yichang from December 2016 to May 2017. After culturing in Roche medium, 367 Mycobacterium tuberculosis isolates were genotyped using the internationally recognised 24 locus MIRU-VNTR system, and the resolution and variation of the MIRU locus was evaluated using the Hunter-Gaston index (HGI) and genetic difference value (h). MIRU-VNTR results were analyzed using BioNumerics 5.0 software to calculate recent transmission rates. The study population of 367 strains, isolated from 367 patients, was subdivided into 321 strains isolated from new TB cases and 46 strains from relapsed cases. Clustering rates were analysed separately for each set of strains. The clustering rates for new and retreated cases were compared using the chi-square test. P<0.05 was considered statistically significant.Results Genotyping of the 367 M.tuberculosis strains using the 24 locus MIRU-VNTR system gave an HGI value of 0.999. The locus with the highest genetic diversity was QUB11b, with an h value of 0.79, and that with the lowest genetic diversity was MIRU24, with an h value of 0.03. A total of 324 genotypes were identified, polymorphisms being evident. Results from clustering analysis indicated that 90 strains formed 39 clusters, with a clustering rate of 24.52% (90/367) and the recent transmission rate of 13.90% (51/367). The clustering rate of strains from relapsed cases (21.74%, 10/46) was not significantly different from that for strains isolated from new cases (24.92%, 80/321) (χ²=0.220, P=0.639).Conclusion Tuberculosis cases in the Yichang area showed high genetic diversity and low transmission rates. Clustering rates were not linked to whether cases were new or relapsed cases.Results suggest that the majority of tuberculosis cases in Yichang are due to endogenous activation. There is also a limited amount of local transmission. Greater attention should be paid to tuberculosis prevention and control in Yichang.