Evaluation of the Analytical Performance of the Xpert MTB/RIF Assay
Evaluation of the Analytical Performance of the Xpert MTB/RIF Assay
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DOI：
10.1128/jcm.00128-10
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发表时间：
2010-07-01
影响因子：
9.4
通讯作者：
Alland, David
中科院分区：
文献类型：
--
作者：
Blakemore, Robert;Story, Elizabeth;Alland, David
我们首次对新的Xpert MTB/RIF方法的分析敏感性、分析特异性和动态范围进行了研究。Xpert MTB/RIF方法是一个基于核酸扩增的诊断系统，可以在不到2小时内检测结核分枝杆菌和利福平(RIF)的耐药性。对79株系统发育和地理上不同的结核分枝杆菌分离株进行了灵敏度测试，其中包括42株药物敏感株和37株RIF耐药株，其中包括13种不同的rpoB突变或突变组合。用89种非结核细菌、真菌和病毒检测了该方法的特异性。Xpert MTB/RIF试验正确识别了所有79个结核分枝杆菌分离株，并正确排除了所有89个非结核分离株。在所有37个耐药株中都正确地鉴定了RIF抗性，而在42个敏感株中没有一个正确地鉴定出RIF抗性。通过在结核杆菌阴性的痰标本中加入10(2)至10(7)个结核分枝杆菌菌落单位来评估动态范围。结果表明，在整个浓度范围内，循环阈值与输入CFU之间呈对数线性关系。在存在不同的RIF抗性和RIF敏感DNA混合物的情况下进行耐药性检测。耐药性检测依赖于特定的突变，要求样本中存在65%至100%的突变DNA，以确保95%的耐药性检测确定性。最后，我们研究了MTBDRplus基因检测产生的交叉污染扩增是否会影响检测的特异性。直到在1毫升的痰中加入至少10(8)个MTBDRplus扩增子，才能检测到结核分枝杆菌，这表明假阳性结果不太可能发生。
We performed the first studies of analytic sensitivity, analytic specificity, and dynamic range for the new Xpert MTB/RIF assay, a nucleic acid amplification-based diagnostic system that detects Mycobacterium tuberculosis and rifampin (RIF) resistance in under 2 h. The sensitivity of the assay was tested with 79 phylogenetically and geographically diverse M. tuberculosis isolates, including 42 drug-susceptible isolates and 37 RIF-resistant isolates containing 13 different rpoB mutations or mutation combinations. The specificity of the assay was tested with 89 nontuberculosis bacteria, fungi, and viruses. The Xpert MTB/RIF assay correctly identified all 79 M. tuberculosis isolates and correctly excluded all 89 nontuberculosis isolates. RIF resistance was correctly identified in all 37 resistant isolates and in none of the 42 susceptible isolates. Dynamic range was assessed by adding 10(2) to 10(7) CFU of M. tuberculosis into M. tuberculosis-negative sputum samples. The assay showed a log-linear relationship between cycle threshold and input CFU over the entire concentration range. Resistance detection in the presence of different mixtures of RIF-resistant and RIF-susceptible DNA was assessed. Resistance detection was dependent on the particular mutation and required between 65% and 100% mutant DNA to be present in the sample for 95% certainty of resistance detection. Finally, we studied whether assay specificity could be affected by cross-contaminating amplicons generated by the GenoType MTBDRplus assay. M. tuberculosis was not detected until at least 10(8) copies of an MTBDRplus amplicon were spiked into 1 ml of sputum, suggesting that false-positive results would be unlikely to occur.