Evaluation of Xpert MTB/RIF Ultra performance on bronchoalveolar lavage fluid samples for pulmonary tuberculosis...

In cases in which tuberculosis is not diagnosed microbiologically through sputum samples, bronchoscopy has been the conventional method to increase diagnostic rates. Few studies have evaluated the performance of the Xpert MTB/RIF Ultra assay on BAL fluid samples. We therefore sought to evaluate the performance of Xpert MTB/RIF Ultra on BAL fluid samples for pulmonary tuberculosis diagnosis in a Brazilian city with a high incidence of tuberculosis.

This was a cross-sectional study performed at a tertiary care university hospital in southern Brazil. Patients > 18 years of age with respiratory symptoms suggestive of pulmonary tuberculosis were invited to participate. Test results were collected, including smear microscopy, mycobacterial culture, and Xpert MTB/RIF Ultra on BAL fluid samples.

During the study period, 161 patients met the inclusion criteria and were therefore included in the analysis. With culture being considered the gold standard, the sensitivity, specificity, positive predictive value, and negative predictive value of Xpert MTB/RIF Ultra on BAL fluid samples were 97.3% (95% CI, 90.6-99.7), 94.3% (95% CI, 87.1-98.1), 93.5% (95% CI, 86.0-97.1), and 97.6% (95% CI, 91.3-99.4), respectively.

The Xpert MTB/RIF Ultra assay showed high sensitivity and specificity on BAL fluid samples from individuals with presumptive pulmonary tuberculosis. This demonstrates that the test is a useful tool for pulmonary tuberculosis diagnosis under programmatic conditions.