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背景:严重耐多药结核(XDR-TB)已成为结核病控制的新威胁,但对其流行病学尚不十分了解。目的:采用分子手段研究南非XDR-TB菌株基因型的人群结构组成,从而确定XDR-TB主要是获得性还是原发感染。方法:收集耐多药结核(MDR-TB)患者的痰菌分离株,送至国家参比实验室进行二线抗结核药物的药敏试验。对XDR-TB的分离株进行Spoligotyping分型,并与该分离株的地理来源相匹配。结果:自2005年6月至2006年12月共获得699例MDR-TB患者的分离株,其中101例(17%)菌株耐氧氟沙星(OFX)或卡那霉素(KAN),41例(6%)对二者均耐药(XDR-TB)。Spoligotyping法将XDR-TB分离株共分为17个基因型。结果表现为高度的基因型多样性和地理分布多样性,所以我们估计63%～75%的XDR-TB患者为获得性耐药。结论:获得性严重耐多药可能是导致南非XDR-TB流行的主要机制。因此结核病控制的迫切问题是必须致力于阻止这种潜在的不治之症的传播。
Background: Severe multidrug-resistant tuberculosis (XDR-TB) has become a new threat to tuberculosis control, but its epidemiology is not well understood. OBJECTIVE: To determine the predominant or primary XDR-TB infection by molecular means to study the population structure of the genotypes of XDR-TB strains in South Africa. Methods: The sputum isolates from patients with multidrug-resistant tuberculosis (MDR-TB) were collected and sent to the national reference laboratories for susceptibility testing of second-line anti-TB drugs. Isolates of XDR-TB were subjected to Spoligotyping and matched to the geographical origin of the isolate. RESULTS: From June 2005 to December 2006, a total of 699 isolates of MDR-TB patients were obtained, of which 101 (17%) strains were resistant to OFX or KAN, 41 Cases (6%) were resistant to both (XDR-TB). The Spoligotyping method divides the XDR-TB isolates into 17 genotypes. The results showed a high degree of genotypic diversity and geographical distribution diversity, so we estimated that 63% to 75% of XDR-TB patients were acquired drug resistance. Conclusions: Acquired severe MDR may be the primary mechanism leading to the prevalence of XDR-TB in South Africa. The pressing issue with tuberculosis control therefore must be to work to stop the spread of this potentially unmanageable disease.