Victor T C, Streicher E M, Kewley C, Jordaan A M, van der Spuy G D, Bosman M, Louw H, Murray M, Young D, van Helden P D, Warren R M
Department of Science and Technology/National Research Foundation (DST/NRF) Centre for Biomedical TB Research/ Medical Research Council (MRC) Centre for Molecular and Cellular Biology, Stellenbosch University, Tygerberg, South Africa.
Int J Tuberc Lung Dis. 2007 Feb;11(2):195-201.
South Africa has a high burden of drug-resistant tuberculosis (TB).
Routine drug susceptibility testing was performed prospectively over a 2-year period on Mycobacterium tuberculosis isolates in two health districts of the Western Province, South Africa. A cluster of drug-resistant strains that shared a rare mutation in katG315 was found in 64 of the 450 cases identified as having been infected with drug-resistant TB. Isolates belonging to this cluster were phenotypically and genotypically characterised. Epidemiological and clinical characteristics were used to identify mechanisms leading to the acquisition and spread of this drug-resistant strain.
An outbreak of an emerging non-Beijing drug-resistant strain infecting 64 pulmonary tuberculosis (PTB) cases was identified. This previously undetected genotype (now designated DRF150) is characterised by five IS6110 insertions, specific spoligotypes and high levels of resistance to the first-line TB medications isoniazid, streptomycin and rifampicin. In 45% of the cases it is also resistant to ethambutol and pyrazinamide. Key factors leading to the development and spread of this drug-resistant genotype were inappropriate chemotherapy, poor adherence to treatment and prolonged periods of infectiousness due to delays in susceptibility testing.
Molecular markers allowed early identification of an emerging non-Beijing drug-resistant strain.
南非耐多药结核病负担沉重。
在南非西开普省的两个卫生区，对结核分枝杆菌分离株进行了为期2年的前瞻性常规药敏试验。在450例确诊为耐多药结核病的病例中，有64例发现了一组在katG315位点存在罕见突变的耐药菌株。对属于该组的分离株进行了表型和基因型特征分析。利用流行病学和临床特征来确定导致这种耐药菌株获得和传播的机制。
确认出现了一种新兴的非北京型耐药菌株感染64例肺结核（PTB）病例的疫情。这种先前未被发现的基因型（现命名为DRF150）的特征是有5个IS6110插入序列、特定的间隔寡核苷酸分型模式以及对一线抗结核药物异烟肼、链霉素和利福平的高耐药水平。在45%的病例中，它还对乙胺丁醇和吡嗪酰胺耐药。导致这种耐药基因型产生和传播的关键因素包括化疗不当、治疗依从性差以及药敏试验延迟导致的传染性持续时间延长。
分子标记物能够早期识别一种新兴的非北京型耐药菌株。
