江西省MDR-TB的MIRU-VNTR分型研究

Genotyping of multi-drug-resistant Mycobacterium tuberculosis from Jiangxi Province with MIRU-VNTR

目的调查江西省耐多药结核分枝杆菌MIRU-VNTR分子特征及传播情况。方法分离自江西地区的耐多药结核分枝杆菌131株,采用15位点MIRU-VNTR进行RD105片段缺乏(北京基因行)检测;进行分型,计算等位点差异、分辨率、成簇率以及近期感染率的估算值。结果江西地区人感染耐多药结核分枝杆菌中北京基因型占83.21%。分离株结核分枝杆菌15位点MIRU-VNTR的HGI值为0.9947,北京家族菌为0.9923。131株菌共分为11个基因簇和98个孤立基因型,成簇率为25.19%,近期感染率估计值为16.79%;北京家族株成簇率为28.44%,近期感染率估计值为19.27%。结论 15位点MIRU-VNTR对包括北京家族株结核分枝杆菌的分辨率高,该方法适合于江西地区耐多药结核分枝杆菌的基因分型。江西省耐多药结核病的流行主要为内源性复燃,但近期传播仍不能忽视。

Objectives To determine the epidemiological and molecular characteristics of multi-drug-resistant Mycobacterium tuberculosis（MDR-TB）in Jiangxi Province using mycobacterial interspersed repetitive unit-variable number tandem repeat typing（MIRU-VNTR）. Methods Strains with RD105 deletion were identified as Beijing family isolates.MDR-TB was genotyped using 15-locus MIRU-VNTR.Allelic diversity and the discriminatory index were calculated,and the cumulative clustering rate and minimum infection rate were estimated. Results The proportion of patients infected with Beijing family isolates of MDR-TB was 83.21%.The Hunter-Gaston discriminatory index for 15 loci was 0.9947,and that for Beijing family isolates was 0.9923.Eleven clusters and 98 unique genotypes were identified,and the clustering rate was 25.19%.The smallest estimated proportion of recent transmission was 16.79%.The clustering rate for Beijing family isolates was 28.44% and the smallest estimated proportion of recent transmission was 19.27%. Conclusion Fifteen-locus MIRU-VNTR had great power to differentiate Beijing family isolates,and it was suitable for genotyping MDR-TB isolates in Jiangxi Province.Outbreaks of MDR-TB in Jiangxi are mainly due to reactivation,but recent transmission has also played a role.