Mlambo C K, Warren R M, Poswa X, Victor T C, Duse A G, Marais E
Clinical Microbiology and Infectious Disease, National Health Laboratory Services, University of the Witwatersrand, Johannesburg, Gauteng, South Africa.
Int J Tuberc Lung Dis. 2008 Jan;12(1):99-104.
The epidemiology of extensively drug-resistant tuberculosis (XDR-TB), an emerging threat to TB control, is not well understood.
To gain insight into the genotypic population structure of XDR Mycobacterium tuberculosis strains in South Africa using a molecular approach and thereby determine whether XDR-TB is mainly acquired or transmitted.
Sputum isolates from patients with multidrug-resistant tuberculosis (MDR-TB) were submitted to the National Referral Laboratory for second-line drug susceptibility testing. The XDR-TB isolates were spoligotyped and these data were compared to the geographic origin of the isolate.
Of the 699 MDR-TB isolates submitted for testing between June 2005 and December 2006, 101 (17%) patients had a culture that was resistant to either ofloxacin or kanamycin, and 41 (6%) were resistant to both drugs (XDR-TB). Spoligotyping of the XDR-TB isolates identified 17 genotypes. As a result of the high genotypic diversity and geographical distribution, we estimate that between 63% and 75% of cases developed XDR-TB through acquisition.
Acquisition of extensive drug resistance appears to be the primary mechanism driving the XDR-TB epidemic in South Africa. This urgent TB control issue has to be addressed to prevent the spread of this potentially incurable disease.
广泛耐药结核病（XDR-TB）是结核病控制面临的新威胁，其流行病学情况尚未完全明了。
采用分子方法深入了解南非广泛耐药结核分枝杆菌菌株的基因型群体结构，从而确定XDR-TB主要是获得性的还是传播性的。
将耐多药结核病（MDR-TB）患者的痰标本送至国家转诊实验室进行二线药物敏感性检测。对XDR-TB分离株进行间隔寡核苷酸分型（spoligotyping），并将这些数据与分离株的地理来源进行比较。
在2005年6月至2006年12月期间提交检测的699株MDR-TB分离株中，101例（17%）患者的培养物对氧氟沙星或卡那霉素耐药，41例（6%）对两种药物均耐药（XDR-TB）。对XDR-TB分离株进行间隔寡核苷酸分型鉴定出17种基因型。由于基因型多样性高且地理分布广泛，我们估计63%至75%的病例是通过获得性感染发展为XDR-TB的。
获得广泛耐药性似乎是推动南非XDR-TB流行的主要机制。必须解决这个紧迫的结核病控制问题，以防止这种潜在的不治之症的传播。
