Terzi Huseyin A, Aydemir Ozlem, Karakece Engin, Koroglu Mehmet, Altindis Mustafa
Clin Lab. 2019 Jan 1;65(1). doi: 10.7754/Clin.Lab.2018.180613.
The objective of this study is to evaluate the performance of the GeneXpert MTB/RIF system in Mycobacterium tuberculosis (MTB) diagnosis and the detection of rifampicin resistance in pulmonary and extrapulmonary clinical samples.
A total of 849 samples (611 pulmonary and 238 extrapulmonary), which were sent to the laboratory of our hospital on suspicion of MTB, were included in the study. The samples cultured on Lowenstein Jensen medium and Mycobacteria Growth Indicator Tubes. All samples were also tested with the GeneXpert MTB/RIF test. The drug susceptibility test was determined using the Bactec MGIT 960 system.
MTB grew in the culture in 84 (9.8%) of all samples, and 78 (9.1%) were found to be positive by the GeneXpert MTB/RIF test, while acid-fast bacillus (AFB), MTB/RIF test, and culture positivity were 41 (6.7%), 74 (12.1%), and 75 (12.3%), respectively, in pulmonary samples, and these values were found to be 2 (0.8%), 4 (1.7%), and 9 (3.8%), respectively, in extrapulmonary samples. In the automated culture and susceptibility system, rifampicin resistance was detected in only one of 84 (2.6%) isolated strains. This resistant strain was also identified by the GeneXpert MTB/RIF test. According to the culture results of all samples examined, the sensitivity of the GeneXpert MTB/RIF test was calculated as 83.3%, specificity as 98.9%, PPV as 89.7%, and NPV as 98.1%.
The GeneXpert MTB/RIF test used in the study was found to be highly successful, very quick, and requiring low workload in pulmonary samples and extrapulmonary samples in terms of sensitivity and specificity. It was observed that it can be used safely due to its high sensitivity, especially in AFB-positive samples.
本研究的目的是评估GeneXpert MTB/RIF系统在肺结核（MTB）诊断以及肺和肺外临床样本中利福平耐药性检测方面的性能。
本研究纳入了我院实验室收到的共849份疑似MTB的样本（611份肺部样本和238份肺外样本）。样本在罗-琴培养基和分枝杆菌生长指示管上培养。所有样本也采用GeneXpert MTB/RIF检测进行检测。使用Bactec MGIT 960系统进行药敏试验。
在所有样本中，84份（9.8%）培养出MTB，GeneXpert MTB/RIF检测发现78份（9.1%）为阳性，而肺部样本中抗酸杆菌（AFB）、MTB/RIF检测及培养阳性率分别为41份（6.7%）、74份（12.1%）和75份（12.3%），肺外样本中这些值分别为2份（0.8%）、4份（1.7%）和9份（3.8%）。在自动化培养和药敏系统中，84株分离菌株中仅1株（2.6%）检测出利福平耐药。该耐药菌株也通过GeneXpert MTB/RIF检测鉴定出来。根据所有检测样本的培养结果，计算出GeneXpert MTB/RIF检测的敏感性为83.3%，特异性为98.9%，阳性预测值为89.7%，阴性预测值为98.1%。
本研究中使用的GeneXpert MTB/RIF检测在肺和肺外样本的敏感性和特异性方面非常成功、快速且工作量低。观察到由于其高敏感性，尤其是在AFB阳性样本中，可以安全使用。
