Yang J, Shen Y, Wang L, et al. - In view of the challenges faced in the bacteriological diagnosis of pulmonary tuberculosis, researchers herein evaluate the diagnostic performance of the Xpert Mycobacterium tuberculosis/Rifampin (MTB/RIF) assay, smear microscopy (SM), and MTB cultures using MTB cultures or final clinical diagnoses as the reference standards. The clinical data from 671 sputum-smear negative or sputum scarce adult patients with suspected PTB who had an Xpert MTB/RIF assay performed on bronchoalveolar lavage fluid (BALF) were retrospectively reviewed. Relative to MTB cultures, Xpert MTB/RIF assay had sensitivity and specificity of 87.8% and 72.7% and SM had sensitivity and specificity of 11.0% and 99.2%, respectively. Relative to final diagnoses, the Xpert MTB/RIF assay showed diagnostic performance of 58.9% and 83.9%, SM showed 5.0% and 98.3%, and culture had 43.3% and 100%, respectively. Overall findings suggest that microbiological evidence was added to clinical decisions by the Xpert MTB/RIF assay on BALF. However, attention should be paid to the ‘very low’ results of this assay which may be false positive.