武汉市耐多药结核分枝杆菌的MIRU-VNTR分子特征

目的 描述武汉市耐多药结核分枝杆菌基因型分布及成簇特征。方法 选取15个结核分枝杆菌重复序列（mycobacterial interspersed repetitive unit，MIRU），对98株耐多药结核分枝杆菌进行多位点数目可变串联重复序列分析（mycobacterial interspersed repetitive unit-variable number tandem repeat typing，MIRU-VNTR）分型，计算差异遗传值、Hunter-Gaston指数（Hunter-Gaston discriminatory index，HGDI）、成簇率以及近期感染率最小估计值。结果 MIRU位点组合的多态性差异遗传值为0.960 4、HGDI为0.970 8，多态性和分辨指数最高的位点为Mtub 21及MIRU 26。共产生7个基因簇和65个独立基因型，成簇率为33.67%，近期感染率最小估计为26.53%。结论 15位点MIRU-VNTR分型法分辨指数较高，适合于武汉地区耐多药结核分枝杆菌的基因分型。尽管武汉市耐多药肺结核病的流行多半归因于内源性复燃，但仍有较高比例的近期传播。

Analysis on genetic diversity of multi-drug-resistant tuberculosis in Wuhan with MIRU-VNTR method

Objective To determine the genotype and cluster characteristics of multi-drug-resistant (MDR) mycobacterium tuberculosis in Wuhan City. Mehtods 98 mycobacterium tuberculosis isolates from MDR tuberculosis (MDR-TB) patients were genotyped by mycobacterial interspersed repetitive unit-variable number tandem repeat typing (MIRU-VNTR). Allelic diversity, Hunter-Gaston discriminatory index (HGDI), cumulative clustering rate and minimum infection rate estimation were calculated. Results The cumulative allelic diversity was 0.960 4. The discriminatory power was 0.970 8. Gene locus with the highest h and HGDI were Mtub21 and MIRU26 respectively. Seven clusters and 65 unique genotype were identified from 98 isolates, and the cluster rate was 33.67% and the least estimated proportion of recent transmission was 26.53%. Conclusions The 15 locus MIRU-VNTR method demonstrate relatively high discriminatory power and it is suitable for MDR mycobacterium tuberculosis isolates genotyping. Although the epidemic of MDR-TB in Wuhan is mainly due to reactivation, there is still a partial contribution from recent transmission.