1 Department of Internal Medicine, 2 Lung Research Institute, 3 Department of Laboratory Medicine, Hallym University College of Medicine, Chuncheon, Korea.
J Thorac Dis. 2014 Jun;6(6):625-31. doi: 10.3978/j.issn.2072-1439.2014.04.12.
Polymerase chain reaction (PCR) for the detection of Mycobacterium tuberculosis (MTB) is more sensitive, specific, and rapid than the conventional methods of acid-fast bacilli (AFB) smear and culture. The aim of this study was to determine if the Xpert MTB/rifampicin (RIF) assay had additional advantages over nested PCR for the detection of MTB in a geographical area with intermediate tuberculosis (TB) incidence.
Between February and December 2013, the Xpert MTB/RIF assay and MTB nested PCR, as well as AFB smear and culture, were simultaneously performed on 198 clinical samples (160 pulmonary and 38 non-pulmonary specimens) collected from 171 patients hospitalized at Hallym University Medical Center for possible TB. The accuracy of the diagnosis of MTB culture-positive TB and the turnaround time of reporting laboratory results were calculated and compared. Rifampin resistance by the Xpert MTB/RIF assay was reviewed with that of conventional drug susceptibility testing (DST).
The sensitivity, specificity, and positive and negative predictive values of the Xpert MTB/RIF assay and MTB nested PCR for diagnosis of MTB culture-positive pulmonary TB were 86.1% vs. 69.4% (P=0.1563), 97.8% vs. 94.1% (P=0.2173), 91.2% vs. 75.8% (P=0.1695), and 96.4% vs. 92.0% (P=0.2032), respectively. The median turnaround times of the Xpert MTB/RIF assay and MTB nested PCR were 0 [0-4] days and 4 [1-11] days, respectively (P<0.001). Two cases of rifampin resistance, as determined by the Xpert MTB/RIF assay, were found to be multi-drug resistant (MDR) pulmonary TB by DST.
The Xpert MTB/RIF assay seemed to be sensitive, specific, and comparable to nested PCR for identifying MTB among clinically suspected TB patients, and the assay can be valuable in giving a timely identification of resistance to rifampin.
聚合酶链反应（PCR）检测结核分枝杆菌（MTB）比传统的抗酸杆菌（AFB）涂片和培养方法更敏感、更特异、更快速。本研究旨在确定在结核病发病率中等的地区，Xpert MTB/rifampicin（RIF）检测是否比巢式 PCR 具有更多优势。
2013 年 2 月至 12 月，对来自 171 例因可能患有结核病而住院于翰林大学医疗中心的 160 例肺部和 38 例非肺部标本的 198 例临床标本同时进行 Xpert MTB/RIF 检测、MTB 巢式 PCR、AFB 涂片和培养。计算并比较 MTB 培养阳性结核病的诊断准确性和报告实验室结果的周转时间。用 Xpert MTB/RIF 检测和常规药敏试验（DST）来评价利福平耐药性。
Xpert MTB/RIF 检测和 MTB 巢式 PCR 诊断 MTB 培养阳性肺结核的敏感性、特异性、阳性预测值和阴性预测值分别为 86.1%比 69.4%（P=0.1563）、97.8%比 94.1%（P=0.2173）、91.2%比 75.8%（P=0.1695）和 96.4%比 92.0%（P=0.2032）。Xpert MTB/RIF 检测和 MTB 巢式 PCR 的中位周转时间分别为 0 [0-4]天和 4 [1-11]天（P<0.001）。通过 Xpert MTB/RIF 检测发现的 2 例利福平耐药性病例，经 DST 证实为耐多药（MDR）肺结核。
Xpert MTB/RIF 检测在识别疑似结核病患者中的 MTB 方面似乎具有敏感性、特异性和与巢式 PCR 相当的优势，该检测方法在及时识别利福平耐药方面具有重要价值。
