Clinical study on lung disease caused by non-tuberculous mycobacteriosis in the elderly

Aim: This study was done to clarify the characteristics of elderly patients with nontuberculous mycobacteriosis. Methods: We investigated the clinical features of 10 patients at an advanced age who had been given diagnosis of nontuberculous mycobacteriosis. Results: Mycobacterium avium intracellulare complex (MAC) were detected in all cases. The age of the patients ranged from 65 to 92. Four cases had underlying respiratory diseases (old pulmonary tuberculosis in 3 cases, pulmonary emphysema in 1 case, bronchiectasia in 1 case). Six cases suffered from dementia. The symptoms were relatively nonspecific, such as low grade fever, fatigue, appetite loss in almost all cases in this study. On computed tomography (CT) scans of the chest, mainly small nodular infiltrates were seen. MAC was detected in clinical samples such as sputum, gastric juice and bronchial lavage. The examination of gastric juice was performed in 6 out of the 10 cases. Gastric juice samples were smear-positive for acid-fast bacilli in 5 of 6, and culture-positive for MAC in 5 of 6. The detection of MAC in gastric juice samples was higher than that in sputum samples on admission. Conclusion: Gastric juice might be useful to differentiate infection from casual isolation of MAC in elderly patients.