The New Xpert MTB/RIF Ultra: Improving Detection of Mycobacterium tuberculosis and Resistance to Rifampin in an Assay Suitable for Point-of-Care Testing.
The New Xpert MTB/RIF Ultra: Improving Detection of Mycobacterium tuberculosis and Resistance to Rifampin in an Assay Suitable for Point-of-Care Testing.
复制标题
新的XPERT MTB/RIF ULTRA：改善了结核分枝杆菌的检测和对利福平的耐药性，适用于适合护理点测试的测定。
DOI：
10.1128/mbio.00812-17
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发表时间：
2017-08-29
期刊：
影响因子：
6.4
通讯作者：
Alland D
中科院分区：
文献类型：
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作者：
Chakravorty S;Simmons AM;Rowneki M;Parmar H;Cao Y;Ryan J;Banada PP;Deshpande S;Shenai S;Gall A;Glass J;Krieswirth B;Schumacher SG;Nabeta P;Tukvadze N;Rodrigues C;Skrahina A;Tagliani E;Cirillo DM;Davidow A;Denkinger CM;Persing D;Kwiatkowski R;Jones M;Alland D
Xpert MTB/RIF Assay（Xpert）是一种结核病（TB）和利福平耐药（RIF-R）快速检测试剂盒，适用于床旁检测。然而，它在痰涂片阴性的敏感性下降，并偶尔发生错误的鉴定RIF-R。我们开发了Xpert MTB/RIF Ultra检测试剂盒（Ultra）以提高性能。对加标已知数量结核分枝杆菌H37 Rv或牛分枝杆菌BCG CFU的结核分枝杆菌DNA或痰液样本进行Ultra和Xpert检测限（LOD）、动态范围和RIF-R rpoB突变检测。还检测了疑似TB患者的冷冻和前瞻性收集的临床样本，包括培养确认的TB和未培养确认的TB。对于结核分枝杆菌H37 Rv，Ultra的LOD为15.6 CFU/ml痰液，Xpert的LOD为112.6 CFU/ml痰液，对于牛分枝杆菌BCG，Ultra的LOD为143.4 CFU/ml痰液，Xpert的LOD为344 CFU/ml痰液。Ultra未产生假阳性RIF-R标本，而Xpert产生了2份假阳性RIF-R标本。所有检测的RIF-R相关结核分枝杆菌rpoB突变均由Ultra鉴定。对临床痰液样本进行检测，Ultra与Xpert的总体灵敏度为87.5%（95%置信区间[CI]，82.1，91.7）与81.0%（95% CI，74.9，86.2），痰涂片阴性样本的灵敏度为78.9%（95% CI，70.0，86.1）vs 66.1%（95% CI，56.4，74.9）。两种检测方法的特异性均为98.7%（95% CI，93.0，100），在这些样本中检测RIF-R的准确性相当。Ultra应能显著提高结核病的检出率，尤其是在少菌性疾病患者中，并可能提供更可靠的RIF-R检测。Xpert MTB/RIF检测试剂盒（Xpert）是首款结核病（TB）即时检测试剂盒，于2010年12月获得世界卫生组织认可。自那时以来，已在130个国家采购了2300万份Xpert检测。尽管Xpert对肺部样本显示出较高的总体灵敏度和特异性，但其对涂片阴性肺部样本和肺外样本的灵敏度较低。此外，在少杆菌样本和少数rpoB突变中预测利福平耐药（RIF-R）导致假阳性和假阴性结果。本研究首次证明了改良Xpert Ultra Assay的设计特征和操作特征。这项研究还表明，Ultra格式克服了Xpert的许多已知缺点。这种新的检测方法将显著提高结核病的检测，特别是在少杆菌病患者中，并提供更可靠的RIF-R检测。
The Xpert MTB/RIF assay (Xpert) is a rapid test for tuberculosis (TB) and rifampin resistance (RIF-R) suitable for point-of-care testing. However, it has decreased sensitivity in smear-negative sputum, and false identification of RIF-R occasionally occurs. We developed the Xpert MTB/RIF Ultra assay (Ultra) to improve performance. Ultra and Xpert limits of detection (LOD), dynamic ranges, and RIF-R rpoB mutation detection were tested on Mycobacterium tuberculosis DNA or sputum samples spiked with known numbers of M. tuberculosis H37Rv or Mycobacterium bovis BCG CFU. Frozen and prospectively collected clinical samples from patients suspected of having TB, with and without culture-confirmed TB, were also tested. For M. tuberculosis H37Rv, the LOD was 15.6 CFU/ml of sputum for Ultra versus 112.6 CFU/ml of sputum for Xpert, and for M. bovis BCG, it was 143.4 CFU/ml of sputum for Ultra versus 344 CFU/ml of sputum for Xpert. Ultra resulted in no false-positive RIF-R specimens, while Xpert resulted in two false-positive RIF-R specimens. All RIF-R-associated M. tuberculosis rpoB mutations tested were identified by Ultra. Testing on clinical sputum samples, Ultra versus Xpert, resulted in an overall sensitivity of 87.5% (95% confidence interval [CI], 82.1, 91.7) versus 81.0% (95% CI, 74.9, 86.2) and a sensitivity on sputum smear-negative samples of 78.9% (95% CI, 70.0, 86.1) versus 66.1% (95% CI, 56.4, 74.9). Both tests had a specificity of 98.7% (95% CI, 93.0, 100), and both had comparable accuracies for detection of RIF-R in these samples. Ultra should significantly improve TB detection, especially in patients with paucibacillary disease, and may provide more-reliable RIF-R detection. The Xpert MTB/RIF assay (Xpert), the first point-of-care assay for tuberculosis (TB), was endorsed by the World Health Organization in December 2010. Since then, 23 million Xpert tests have been procured in 130 countries. Although Xpert showed high overall sensitivity and specificity with pulmonary samples, its sensitivity has been lower with smear-negative pulmonary samples and extrapulmonary samples. In addition, the prediction of rifampin resistance (RIF-R) in paucibacillary samples and for a few rpoB mutations has resulted in both false-positive and false-negative results. The present study is the first demonstration of the design features and operational characteristics of an improved Xpert Ultra assay. This study also shows that the Ultra format overcomes many of the known shortcomings of Xpert. The new assay should significantly improve TB detection, especially in patients with paucibacillary disease, and provide more-reliable detection of RIF-R.