The utility of Xpert MTB/RIF performed on bronchial washings obtained in patients with suspected pulmonary tuberculosis in a high prevalence setting

Date
2015-09
Authors
Barnard, Dewald A.
Irusen, Elvis M.
Bruwer, Johannes W.
Plekker, Dante
Whitelaw, Andrew C.
Deetlefs, Jacobus D.
Koegelenberg, Coenraad F. N.
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
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.
Description
The original publication is available at http://www.biomedcentral.com/content/pdf/s12890-015-0086-z.pdf
Publication of this article was funded by the Stellenbosch University Open Access Fund.
Keywords
Tuberculosis, Xpert MTB/RIF
Citation
Barnard, D. A. et al. 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(103), doi:10.1186/s12890-015-0086-z.