Diagnostic accuracy of Xpert MTB/RIF Ultra in bronchial aspirate specimens for microbiological confirmation of pulmonary tuberculosis in patients with negative smear and Xpert MTB/RIF Ultra results in sputum

<bold>Introduction:</bold> Worldwide up to one third of pulmonary tuberculosis (PTB) patients missed microbiological confirmation. Assessment of specimens obtained during bronchoscopy is one of the well-recognised methods to increase rate of microbiological confirmation in PTB. The data on diagnostic accuracy of Xpert MTB/RIF Ultra in bronchial aspirate (BA) specimen are very limited. <bold>Aim:</bold> To evaluated diagnostic accuracy of Xpert MTB/RIF Ultra in BA in patients with negative smear microscopy and Xpert MTB/RIF Ultra in sputum. <bold>Methods:</bold> We retrospectively reviewed microbiological and basic clinical characteristics of all patients who were consulted for suspected PTB at the Institute of Phthisiopneumology in Moldova during 2022 and had both negative smear and Xpert MTB/RIF Ultra results in sputum and in whom BA was obtained through bronchoscopy for further examination by Xpert MTB/RIF Ultra and culture for <italic>M. tuberculosis.</italic> <bold>Results:</bold> 393 cases with complete dataset have been analysed, of them 80 have been diagnosed with PTB. Positive culture for <italic>M. tuberculosis</italic> was obtained in 2.5% (10/393), smear microscopy was positive in 1.8% (7/393) and Xpert MTB/RIF Ultra in 2.3% (9/393) of BAs. The sensitivity and specificity of Xpert MTB/RIF Ultra in BA, using culture as reference standard, were correspondingly 80.0% (95%CI, 37.5% – 99.0%) and 98.7% (95%CI, 97.0% - 99.4%). Rapid microbiological confirmation of PTB was obtained in 11.2% (9/80) of the patients diagnosed with PTB. <bold>Conclusion:</bold> Xpert MTB/RIF Ultra has a good diagnostic accuracy in BA samples in patients with extremely paucibacillary sputum.