Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.
J Clin Microbiol. 2012 Sep;50(9):2857-62. doi: 10.1128/JCM.00358-12. Epub 2012 May 30.
Despite South Africa being one of the high-burden multidrug-resistant tuberculosis (MDR-TB) countries, information regarding the population structure of drug-resistant Mycobacterium tuberculosis strains is limited from many regions of South Africa. This study investigated the population structure and transmission patterns of drug-resistant M. tuberculosis isolates in a high-burden setting of South Africa as well as the possible association of genotypes with drug resistance and demographic characteristics. A total of 336 consecutive MDR-TB isolates from four provinces of South Africa were genotyped using spoligotyping and mycobacterial interspersed repetitive-unit-variable number tandem repeat (MIRU-VNTR) typing. Drug susceptibility testing for ofloxacin, kanamycin, and capreomycin was performed using the agar proportion method. The results showed that 4.8% of MDR-TB isolates were resistant to ofloxacin, 2.7% were resistant to kanamycin, and 4.5% were resistant to capreomycin, while 7.1% were extensively drug resistant (XDR), and the remaining 83.6% were susceptible to all of the second-line drugs tested. Spoligotyping grouped 90.8% of the isolates into 25 clusters, while 9.2% isolates were unclustered. Ninety-one percent of the 336 isolates were assigned to 21 previously described shared types, with the Beijing family being the predominant genotype in the North-West and Limpopo Provinces, while the EAI1_SOM family was the predominant genotype in the Gauteng and Mpumalanga Provinces. No association was found between genotypes and specific drug resistance patterns or demographic information. The high level of diversity and the geographical distribution of the drug-resistant M. tuberculosis isolates in this study suggest that the transmission of TB in the study settings is not caused by the clonal spread of a specific M. tuberculosis strain.
尽管南非是耐多药结核病（MDR-TB）负担较高的国家之一，但来自南非许多地区的关于耐药结核分枝杆菌菌株人群结构的信息有限。本研究调查了南非高负担地区耐药 M. tuberculosis 分离株的人群结构和传播模式，以及基因型与耐药性和人口统计学特征的可能关联。总共对南非四个省的 336 例连续 MDR-TB 分离株进行 spoligotyping 和分枝杆菌插入重复单元可变数串联重复（MIRU-VNTR）分型。使用琼脂比例法对氧氟沙星、卡那霉素和卷曲霉素进行药物敏感性测试。结果显示，4.8%的 MDR-TB 分离株对氧氟沙星耐药，2.7%对卡那霉素耐药，4.5%对卷曲霉素耐药，而 7.1%为广泛耐药（XDR），其余 83.6%对所有测试的二线药物敏感。 spoligotyping 将 90.8%的分离株分为 25 个簇，而 9.2%的分离株未聚类。336 株分离株中有 91%被分配到 21 个先前描述的共享型中，其中北京家族在西北省和林波波省占主导地位，而 EAI1_SOM 家族在豪登省和姆普马兰加省占主导地位。基因型与特定耐药模式或人口统计学信息之间未发现关联。本研究中耐药 M. tuberculosis 分离株的多样性和地理分布水平较高，表明研究环境中的结核病传播不是由特定 M. tuberculosis 菌株的克隆传播引起的。
