Key Laboratory of Bio-resources and Eco-environment, Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan 610064, PR China.
Infect Genet Evol. 2012 Jun;12(4):718-24. doi: 10.1016/j.meegid.2011.09.022. Epub 2011 Oct 2.
China ranks second next to India among 22 high-burden countries despite decades' effort on tuberculosis (TB) control. The Sichuan province today contains the second-largest number of TB cases among Chinese provinces, where the prevalence of drug-resistant TB, especially MDR-TB, is much higher than the average level in eastern China. In this study, the population structure and the transmission characteristics of drug-resistant TB in Sichuan province were studied by spoligotyping and 24-locus Mycobacterial interspersed repetitive units-variable number tandem DNA repeats (MIRU-VNTR), applied to a total of 306 clinical isolates. Spoligotyping-based analysis showed that Beijing family represented 69.28% of all isolates and constituted the largest group (66.24%) of MDR-TB in Sichuan. The remaining isolates, accounting for 33.76% of MDR isolates, belonged to the ill-defined T family, Manu2, H3, LAM9, and other minor unassigned clades. The discriminatory power evaluated for spoligotyping was poor (HGI=0.595), but high for 24-locus MIRU-VNTRs (HGI=0.999). The number of the most discriminatory loci (h>0.6) was 12, including locus 424, 802, 960, 1644, 1955, 2163b, 2996, 3007, 3192, 3690, 4348 and 4052. It was concluded that 24-locus MIRU-VNTRs could be a more discriminatory tool for differentiating clinical isolates from Sichuan region. The small clustering size obtained from the current population structure analysis suggested that the high prevalence of drug-resistant TB in this region might be attributed partially to the acquired resistance due to inappropriate drug use rather than active transmission of drug-resistant TB (primary resistance).
中国在结核病（TB）控制方面虽然已经努力了几十年，但在 22 个高负担国家中仍仅次于印度排名第二。四川省是中国 TB 病例第二多的省份，其耐药 TB，特别是耐多药 TB（MDR-TB）的流行率远高于中国东部地区的平均水平。在这项研究中，通过 spoligotyping 和 24 位位点分枝杆菌插入重复单元-可变数串联重复 DNA 重复（MIRU-VNTR）对四川省的耐药 TB 人群结构和传播特征进行了研究，共涉及 306 株临床分离株。 spoligotyping 分析显示，北京家族占所有分离株的 69.28%，是四川省 MDR-TB 最大的一组（66.24%）。其余分离株占 MDR 分离株的 33.76%，属于定义不明确的 T 家族、Manu2、H3、LAM9 和其他少数未分配的分支。 spoligotyping 的分辨力评估较差（HGI=0.595），但 24 位 MIRU-VNTRs 的分辨力较高（HGI=0.999）。最具分辨力的位点数（h>0.6）为 12 个，包括位 424、802、960、1644、1955、2163b、2996、3007、3192、3690、4348 和 4052。结论认为，24 位 MIRU-VNTRs 可能是区分四川地区临床分离株的更具分辨力的工具。当前人群结构分析得到的聚类规模较小表明，该地区耐药性 TB 的高流行率可能部分归因于不合理用药导致的获得性耐药，而不是耐药性 TB 的主动传播（原发性耐药）。
