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Updated: May 11, 2026

Diagnosing Pulmonary Tuberculosis with the Xpert MTB/RIF Test
Published on: April 9, 2012
Diagnostic accuracy of Xpert® MTB/RIF on bronchoscopy specimens in patients with suspected pulmonary tuberculosis
1Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and Lung Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.
Objective:
To determine the diagnostic accuracy of the Xpert® MTB/RIF assay using samples obtained through bronchoscopy in patients with suspected pulmonary tuberculosis (PTB).
Design:
We retrospectively reviewed the records of patients with suspected PTB for whom the Xpert MTB/RIF assay was performed on bronchoscopy specimens. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the diagnosis of active PTB were calculated for acid-fast bacilli (AFB) smear microscopy and the Xpert assay using culture of Mycobacterium tuberculosis from sputum or bronchoscopy specimens as a reference standard.
Results:
A total of 132 patients were included in the final analysis. Of these, 38 had culture-confirmed PTB. The sensitivity of the Xpert assay using bronchial washing or bronchoalveolar lavage (BAL) fluid for the diagnosis of PTB was 81.6%, and specificity was 100%. The PPV and NPV were 100% and 92.1%, respectively. The sensitivity and specificity of AFB smear microscopy were respectively 13.2% and 98.8%.
Conclusion:
The Xpert assay on bronchoscopy specimens provided an accurate diagnosis of PTB in patients who had a negative AFB smear or who could not produce sputum.
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