Yield of Sputum Induction in the Diagnosis of Pleural Tuberculosis

We prospectively evaluated the diagnostic yield of acid-fast bacilli smear and culture for Mycobacterium tuberculosis using sputum induction (SI) in the workup of patients with suspected pleural tuberculosis (TB) who were unable to produce sputum spontaneously. Of the 113 patients studied, a final diagnosis of pleural TB was made in 84 patients (71 HIV seronegative) and a final diagnosis of another disease in 29 patients. Histopathologic examination of the pleural biopsy tissue had the highest diagnostic yield (78%; 66/84). The bacteriologic yield was 62% (52/84) for the pleural tissue, 12% (10/84) for pleural fluid, and 52% (44/84) for sputum cultures obtained by SI. The yield of SI culture for M. tuberculosis was 55% (35/64) in patients with a normal radiograph (except for the pleural effusion) and 45% (9/20) in those with evidence of parenchymal disease suggestive of pulmonary TB (p = 0.6). The yield of sputum cultures obtained by SI is high in patients suspected of having pleural TB even in those cases with no pulmonary parenchymal abnormalities on the chest radiograph.