Clinical application of fluorescent quantitative PCR in detection of patients with extra-pulmonary tuberculosis

Abstract

Objective To evaluate the effect of GeneXpert Mycobacterium tuberculosis/Rifampin (GeneXpert MTB/RIF) in detection of Mycobacterium tuberculosis in pericardial and pleural effusion samples. Methods From January 2015 to June 2017, data of 286 suspected cases with tuberculosis were collected from The First people’s Hospital and Hanchuan People’s Hospital. There were 158 cases with pleural effusion and 128 cases with pericardial effusion, respectively. Each sample was examined by acid fast staining, smear microscopy, LJ Culture and GeneXpert MTB/RIF assay, respectively. Taking Mycobacterium LJ culture as the gold standard, the effect of GeneXpert MTB/RIF in detecting MTB was evaluated. Results Among the 286 effusion samples, 5 (17.8%) were MTB positive for LJ cultured, 43 (15%) were MTB positive determined by GeneXpert MTB/RIF, and 11 (3.8%) were MTB positive detected by acid-fast stain microscopy. The sensitivity, specificity, positive predictive value and negative predictive value of GeneXpert technology were 84.3%, 100%, 100% and 84.3%, respectively; while those of the acid fast stain method were 18.3%, 99.1%, 81.8% and 99.1%, respectively. The sensitivity of MTB in pericardial effusion was up to 90% detected by GeneXpert. GeneXpert MTB/RIF and acid-fast stain microscopy showed significant difference in the identification of Mycobacterium tuberculosis in two samples (χ2 = 233.199, 33.715; all P < 0.001). Conclusion GeneXpert MTB/RIF technology has high sensitivity and specificity on detecting MTB in pleural effusion and pericardial effusion. Key words: Tuberculous pleurisy; Tuberculous pericarditis; GeneXpert Mycobacterium tuberculosis/Rifampin; Extrapulmonary tuberculosis