Diagnostic accuracy of different bronchoscopic specimens in sputum Xpert MBT/RIF- negative pulmonary TB patients

Tuberculosis (TB) control remains a critical public health problem worldwide. Rapid diagnosis and proper treatment are beneficial for the effective control of tuberculosis transmission. Diagnostic challenges arise when a patient has a clinical and radiological suspicion of tuberculosis but cannot produce sputum, sputum acid-fast bacilli, or Xpert Mycobacterium tuberculosis/rifampicin (Xpert MTB/RIF) is negative, resulting in suboptimal management. As a result, more invasive techniques must be used on these patients to establish the diagnosis.

A retrospective study recruited 330 suspected pulmonary TB patients with negative sputum of Xpert MBT/RIF who underwent bronchoscopy between March 2018 and December 2021. The diagnostic yields of bronchoalveolar lavage fluid (acid-fast bacilli, Xpert MTB/RIF, and culture) and histopathologic examination (HPE) were calculated and compared to the final diagnosis and culture as a gold standard.

Out of 330 suspected pulmonary TB patients, 181 had a final diagnosis of TB, and 149 had non-TB. The sensitivity of BALF (culture, Xpert, acid-fast bacilli) and trans-bronchial lung biopsy (HPE) was 80.7%, 72.9%, 21.1%, and 87.1%, respectively. Multiple nodules were associated with significantly higher BALF Xpert MTB, bronchoalveolar lavage fluid culture, and trans-bronchial lung biopsy (HPE) positivity.

Bronchoscopic specimens are essential for accurate and rapid diagnosis of sputum Xpert MBT/RIF negative patients with high clinical and radiological suspicion of tuberculosis.