Division of Infectious Diseases and Tropical Medicine, Medical Center of the University of Munich (LMU), Munich, Germany.
PLoS One. 2011;6(6):e20458. doi: 10.1371/journal.pone.0020458. Epub 2011 Jun 29.
A crucial impediment to global tuberculosis control is the lack of an accurate, rapid diagnostic test for detection of patients with active TB. A new, rapid diagnostic method, (Cepheid) Xpert MTB/RIF Assay, is an automated sample preparation and real-time PCR instrument, which was shown to have good potential as an alternative to current reference standard sputum microscopy and culture.
We performed a clinical validation study on diagnostic accuracy of the Xpert MTB/RIF Assay in a TB and HIV endemic setting. Sputum samples from 292 consecutively enrolled adults from Mbeya, Tanzania, with suspected TB were subject to analysis by the Xpert MTB/RIF Assay. The diagnostic performance of Xpert MTB/RIF Assay was compared to standard sputum smear microscopy and culture. Confirmed Mycobacterium tuberculosis in a positive culture was used as a reference standard for TB diagnosis.
Xpert MTB/RIF Assay achieved 88.4% (95%CI = 78.4% to 94.9%) sensitivity among patients with a positive culture and 99% (95%CI = 94.7% to 100.0%) specificity in patients who had no TB. HIV status did not affect test performance in 172 HIV-infected patients (58.9% of all participants). Seven additional cases (9.1% of 77) were detected by Xpert MTB/RIF Assay among the group of patients with clinical TB who were culture negative. Within 45 sputum samples which grew non-tuberculous mycobacteria the assay's specificity was 97.8% (95%CI = 88.2% to 99.9%).
The Xpert MTB/RIF Assay is a highly sensitive, specific and rapid method for diagnosing TB which has potential to complement the current reference standard of TB diagnostics and increase its overall sensitivity. Its usefulness in detecting sputum smear and culture negative patients needs further study. Further evaluation in high burden TB and HIV areas under programmatic health care settings to ascertain applicability, cost-effectiveness, robustness and local acceptance are required.
全球结核病控制的一个关键障碍是缺乏准确、快速的诊断检测方法来检测活动性结核病患者。一种新的快速诊断方法（Cepheid）Xpert MTB/RIF 检测，是一种自动化的样本制备和实时 PCR 仪器，已被证明具有替代当前参考标准痰涂片显微镜检查和培养的潜力。
我们在坦桑尼亚姆贝亚的一个结核病和艾滋病毒流行地区进行了一项关于 Xpert MTB/RIF 检测诊断准确性的临床验证研究。对 292 例连续入组的疑似结核病成人的痰液样本进行了 Xpert MTB/RIF 检测分析。Xpert MTB/RIF 检测的诊断性能与标准痰涂片显微镜检查和培养进行了比较。阳性培养物中的确诊结核分枝杆菌被用作结核病诊断的参考标准。
Xpert MTB/RIF 检测在培养阳性的患者中达到 88.4%（95%CI=78.4%至 94.9%）的敏感性，在无结核病的患者中达到 99%（95%CI=94.7%至 100.0%）的特异性。在 172 例 HIV 感染患者（所有参与者的 58.9%）中，HIV 状态并未影响检测性能。在培养阴性的临床结核病患者中，Xpert MTB/RIF 检测还额外检测到 7 例（77 例中的 9.1%）病例。在 45 例培养出非结核分枝杆菌的痰液样本中，该检测的特异性为 97.8%（95%CI=88.2%至 99.9%）。
Xpert MTB/RIF 检测是一种高度敏感、特异和快速的结核病诊断方法，具有补充当前结核病诊断参考标准并提高其总体敏感性的潜力。其在检测痰涂片和培养阴性患者中的作用需要进一步研究。需要在方案性卫生保健环境下的高负担结核病和艾滋病毒地区进一步评估，以确定适用性、成本效益、稳健性和当地接受程度。
