Incremental yield of bronchial washing for diagnosing smear-negative pulmonary tuberculosis

To assess the increased diagnostic yield for pulmonary tuberculosis using bronchial washing cultures compared with sputum cultures.

Study conducted with 61 adults in Lima, Peru, from January 2006 to December 2007. The yield of sputum cultures was compared with the yield of acid-fast bacilli smears and cultures of bronchial washing for diagnosing pulmonary tuberculosis in suspected cases of clinical tuberculosis with negative acid fast bacilli sputum smears.

Twenty seven (95%CI 32;58) of the cases were eventually diagnosed with smear-negative pulmonary tuberculosis. Bronchial washing samples detected 23 (95%CI 72;99) of the smear-negative pulmonary tuberculosis cases compared with 15 (95%CI 37;74) for sputum cultures (p = 0.02). The incremental diagnostic yield of acid fast bacilli smear and culture of bronchial washing specimens over sputum culture was 44% (95%CI 25;65).

In function of the epidemiological context and the resources available, bronchoscopy should be deployed as part of a comprehensive work up that optimizes smear-negative pulmonary tuberculosis diagnosis and minimizes risk and costs.