Mazzola Ester, Arosio Marco, Nava Alice, Fanti Diana, Gesu Giovanni, Farina Claudio
Microbiology Laboratory, ASST Grande Ospedale Metropolitano Niguarda, Milan, Italy.
Microbiology Institute, ASST Papa Giovanni XXIII, Bergamo, Italy.
Infez Med. 2016 Dec 1;24(4):304-309.
The real time PCR Xpert ® MTB/RIF is fundamental for rapid diagnosis in paucibacillary respiratory samples and for the detection of multidrug-resistant TB cases. This paper aimed to determine its performance on different extrapulmonary samples. We determined sensitivity, specificity, positive and negative predictive value on respiratory and non-respiratory samples collected from January 2010 to June 2014. The protocol for the Xpert ® MTB/RIF PCR suggested by Cepheid was strictly followed for all specimens. In 12257 respiratory samples we observed a sensitivity of 87.1% and a specificity of 99.9%. There were 2818 extrapulmonary specimens, of which 250 were followed by a positive culture for Mycobacterium tuberculosis complex, whereas 72 samples were culture-negative: tuberculosis was clinically confirmed in 71 of them and was excluded for one sample. The sensitivity of the test on urine, pus and CSF samples was 88.2%, 95.6% and 100% respectively. In contrast, the sensitivity of gastric aspirates and biopsies was 81.8% and 83.6% respectively, whereas results of total cavitary fluids were significantly worse than expected (53.7% sensitivity). Our experience shows that Xpert MTB/RIF assay is an accurate, sensitive, and specific test for the rapid detection of pulmonary and extra-pulmonary TB with the only exception of cavitary fluids.
实时荧光定量PCR Xpert® MTB/RIF对于痰菌阴性呼吸道样本的快速诊断以及耐多药结核病病例的检测至关重要。本文旨在确定其在不同肺外样本上的性能。我们测定了2010年1月至2014年6月期间收集的呼吸道和非呼吸道样本的敏感性、特异性、阳性预测值和阴性预测值。所有标本均严格遵循Cepheid公司建议的Xpert® MTB/RIF PCR检测方案。在12257份呼吸道样本中,我们观察到敏感性为87.1%,特异性为99.9%。有2818份肺外标本,其中250份随后结核分枝杆菌复合群培养呈阳性,而72份样本培养阴性:其中71份临床确诊为结核病,1份样本排除结核病。该检测对尿液、脓液和脑脊液样本的敏感性分别为88.2%、95.6%和100%。相比之下,胃液抽吸物和活检样本的敏感性分别为81.8%和83.6%,而空洞液总体结果明显差于预期(敏感性为53.7%)。我们的经验表明,Xpert MTB/RIF检测对于快速检测肺结核和肺外结核是一种准确、敏感且特异的检测方法,唯一例外的是空洞液样本。