Simultaneous amplification and testing method for Mycobacterium tuberculosis rRNA to differentiate sputum-negative tuberculosis from sarcoidosis

We use the simultaneous application and testing method to detect Mycobacterium tuberculosis rRNA (SAT-TB) with the endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) biopsy specimens to differentiate sputum-negative tuberculosis from sarcoidosis. In the first part, we validated the SAT-TB on the bronchial or EBUS-TBNA biopsy specimens from sputum smear-positive pulmonary tuberculosis. In the second part, all EBUS-TBNA specimens for sputum smear-negative intrathoracic tuberculous lymphadenopathies or sarcoidosis were tested with the SAT-TB, acid-fast bacilli smear, and culture. In the 16 sputum-positive tuberculosis cases, 5 showed negative SAT (2 nontuberculous mycobacteria and 3 had anti-tuberculosis therapies previously); the remaining 11 were positive. Of the 41 sputum-negative tuberculosis cases in the second part, five other diseases were negative. In the remaining 36 cases, 27 sarcoidosis cases were negative; 7 in 9 with sputum-negative tuberculosis were positive (77.78%). In these 36 patients, the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the SAT method were 77.78, 100, 100, 93.10, and 94.44%, respectively. The SAT distinguished sputum-negative tuberculosis from sarcoidosis significantly ( P < 0.0001) and identified cases with active M. tuberculosis as accurately as the conventional methods (κ = 0.912, P < 0.0001). We conclude that the SAT-TB may be an effective method for using biopsy specimens to differentiate sputum-negative tuberculosis from sarcoidosis.