Background: Xpert MTB/RIF has been shown to have a superior sensitivity to microscopy for acid fast bacilli (AFB) in sputum and has been recommended as a standard first line investigation for pulmonary tuberculosis (PTB). Bronchoscopy is a valuable tool in diagnosing PTB in sputum negative patients. There is limited data on the utility of Xpert MTB/RIF performed on bronchial lavage specimens. Our aim was to evaluate the diagnostic efficiency of Xpert MTB/RIF performed on bronchial washings in sputum scarce/negative patients with suspected PTB. Methods: All patients with a clinical and radiological suspicion of PTB who underwent bronchoscopy between January 2013 and April 2014 were included. The diagnostic efficiencies of Xpert MTB/RIF and microscopy for AFB were compared to culture for Mycobacterium tuberculosis. Results: Thirty nine of 112 patients were diagnosed with culture-positive PTB. Xpert MTB/RIF was positive in 36/39 with a sensitivity of 92.3% (95 % CI 78-98%) for PTB, which was superior to that of smear microscopy (41%; 95 % CI 26.0-57.8%, p = 0.005). The specificities of Xpert MTB/RIF and smear microscopy were 87.7% (95 % CI 77.4-93.9%) and 98.6% (95 % CI 91.6%-99.9%) respectively. Xpert MTB/RIF had a positive predictive value of 80% (95 % CI; 65-89.9%) and negative predictive value of 95.5% (95 % CI 86.6-98.8%). 3/9 patients with Xpert MTB/RIF positive culture negative results were treated for PTB based on clinical and radiological findings. Conclusion: Xpert MTB/RIF has a higher sensitivity than smear microscopy and similar specificity for the immediate confirmation of PTB in specimens obtained by bronchial washing, and should be utilised in patients with a high suspicion of pulmonary tuberculosis.
CITATION STYLE
Barnard, D. A., Irusen, E. M., Bruwer, J. W., Plekker, D., Whitelaw, A. C., Deetlefs, J. D., & Koegelenberg, C. F. N. (2015). The utility of Xpert MTB/RIF performed on bronchial washings obtained in patients with suspected pulmonary tuberculosis in a high prevalence setting. BMC Pulmonary Medicine, 15(1). https://doi.org/10.1186/s12890-015-0086-z
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