Evaluation of Xpert MTB/RIF in detection of pulmonary and extrapulmonary tuberculosis cases in China

Background: To evaluate the performance of Xpert MTB/RIF assay for direct detection of Mycobacterium tuberculosis (Mtb) and rifampin resistance in pulmonary and extrapulmonary tuberculosis (TB) patients in China. Material/Methods: We prospectively enrolled 506 TB patients to evaluate sensitivity and specificity of Xpert MTB/ RIF by comparing with Mtb culture, fluorescent staining smear microscopy and clinical diagnosis. Results: Overall, 402 of 506 (79.4%) included patients were clinically diagnosed with TB. Sensitivities of Xpert MTB/RIF, Mtb culture, and AFB microscopy, and combined three methods among clinically-diagnosed pulmonary TB patients were 67.7% (130/192), 65.1% (125/192), 61.5% (118/192), and 69.8% (134/192) respectively; and 19.0% (40/210), 23.8% (50/210), 5.2% (11/210), and 34.3% (72/210) respectively among clinically-diagnosed extrapulmonary TB patients. Specificities of Xpert MTB/RIF assay for pulmonary and extrapulmonary TB were 100%. Compared with MGIT drug susceptibility test, the sensitivity and specificity of Xpert MTB/RIF for diagnosis of rifampin-resistant TB was 77.3% and 96.0% respectively. Conclusion: The Xpert MTB/RIF assay has a comparable sensitivity with Mtb culture for pulmonary TB, but less sensitive than Mtb culture for extrapulmonary TB. Combined three methods achieved a better sensitivity than any individual test.