IML red, Supranational Reference Laboratory of Tuberculosis, Gauting, Germany.
BMC Infect Dis. 2013 Jun 20;13:280. doi: 10.1186/1471-2334-13-280.
Nucleic acid amplification assays allow for the rapid and accurate detection of Mycobacterium tuberculosis (MTB) directly in clinical specimens thereby facilitating diagnosis of tuberculosis (TB). With the fully automated Xpert MTB/RIF system (Cepheid) an innovative solution of TB diagnostics has been launched. We performed a direct head-to-head comparison of Xpert MTB/RIF with two widely used commercial assays, ProbeTec ET DTB (DTB) (Becton-Dickinson) and COBAS TaqMan MTB (CTM-MTB) (Roche).
121 pre-characterized respiratory specimens (68 culture-positive for MTB complex, 24 culture-positive for non-tuberculous mycobacteria and 29 culture-negative) taken from our frozen specimen bank were tested for the presence of MTB complex by the three assays.
Among culture-positive samples (n = 68), overall sensitivity for detection of MTB complex was 74.6%, 73.8%, and 79.1% for Xpert MTB/RIF, CTM-MTB, and DTB, respectively. Within the subgroup of smear-negative TB samples (n = 51) sensitivity was 68% for Xpert MTB/RIF and CTM-MTB and 72% for DTB. Among smear-positive TB samples (n = 17), all (100%) were detected by DTB and 94.1% and 93.3% by Xpert MTB/RIF and CTM-MTB, respectively. Specificity was best for CTM-MTB (100%) and lowest for Xpert MTB/RIF (96.2%) due to misidentification of two NTM samples as MTB complex. CTM-MTB yielded the highest rate of invalid results (4.1%) (0.8% by Xpert MTB/RIF and DTB, respectively).
The direct comparison of Xpert MTB/RIF with CTM-MTB and DTB yielded similar overall performance data. Whereas DTB was slightly superior to Xpert MTB/RIF in terms of sensitivity, at least in the sample collection tested here, CTM-MTB performed best in terms of specificity.
核酸扩增检测可直接从临床标本中快速准确地检测结核分枝杆菌（MTB），从而有助于结核病（TB）的诊断。随着全自动 Xpert MTB/RIF 系统（Cepheid）的推出，一种创新性的结核病诊断解决方案已经问世。我们对 Xpert MTB/RIF 与两种广泛使用的商业检测方法——ProbeTec ET DTB（DTB）（Becton-Dickinson）和 COBAS TaqMan MTB（CTM-MTB）（罗氏）进行了直接的头对头比较。
我们从冷冻标本库中选取了 121 例已预先确定特征的呼吸道标本（68 例培养阳性的 MTB 复合体、24 例培养阳性的非结核分枝杆菌和 29 例培养阴性），用三种检测方法检测 MTB 复合体的存在。
在培养阳性的样本中（n=68），Xpert MTB/RIF、CTM-MTB 和 DTB 检测 MTB 复合体的总敏感性分别为 74.6%、73.8%和 79.1%。在痰涂片阴性的 TB 样本亚组中（n=51），Xpert MTB/RIF 和 CTM-MTB 的敏感性为 68%，DTB 为 72%。在痰涂片阳性的 TB 样本中（n=17），所有样本（100%）均被 DTB 检测到，Xpert MTB/RIF 和 CTM-MTB 的检出率分别为 94.1%和 93.3%。由于两种 NTM 样本被误识别为 MTB 复合体，特异性最好的是 CTM-MTB（100%），最低的是 Xpert MTB/RIF（96.2%）。CTM-MTB 的无效结果率最高（4.1%）（Xpert MTB/RIF 和 DTB 分别为 0.8%和 0.8%）。
Xpert MTB/RIF 与 CTM-MTB 和 DTB 的直接比较得出了相似的总体性能数据。虽然在敏感性方面，DTB 略优于 Xpert MTB/RIF，但在本研究中测试的样本中，CTM-MTB 的特异性最好。
