Bronchial wash culture is less valuable in patients suspected to have nontuberculous mycobacteria lung disease for bilateral bronchiectasis with nodules

Backgrounds: Bronchiectasis (BE) with nodules on chest computed tomography (CT) is one of the radiological findings of nontuberculous mycobacteria (NTM) lung disease. However, the NTM lung disease is not diagnosed in some patients who undergo bronchoscopy, though their radiological findings show BE with nodules. We need the indicator to distinguish the patients who would not be given the diagnosis of NTM lung disease with bronchoscopy. Methods: We retrospectively reviewed the records of the patients who underwent bronchoscopy from January 2010 to July 2013 at our hospital because sputum test had not yielded the diagnosis of NTM lung disease or the patients had been unable to produce sputum, though their chest CT had shown BE with nodules. Results: A total of 36 patients were included in this study, and acid-fast bacterium (AFB) culture of bronchial wash was positive in 17 patients. More patients with negative culture in bronchial wash had AFB-negative culture with purulent sputum before bronchoscopy (37% vs. 0%, P = 0.008) and bilateral BE with nodules on chest CT (89% vs. 41%, P = 0.007). Multivariate analysis showed that bilateral BE with nodules on chest CT was the risk factor for the negative culture of AFB with bronchial wash (odds ratio: 0.149; 95% confidence interval: 0.024–0.913, P = 0.040). Conclusion: Patients with bilateral BE with nodules on chest CT have less possibility to have positive AFB culture from bronchial wash when sputum test was not diagnostic.