Nontuberculous mycobacteria in patients with cystic fibrosis

OBJECTIVE: Patients with cystic fibrosis are at great risk of infection by nontuberculous mycobacteria from the environment because of certain predisposing factors such as bronchiectasis, malnutrition, and diabetes. The aim of this study was to analyze the mycobacterial content of sputum smears and cultures from adult patients with cystic fibrosis attended at a specialized unit for adults from March 1997 through December 2001. PATIENTS AND METHODS: Sputum samples were collected prospectively according to a protocol applied at each visit, and during most exacerbations staining and culture for mycobacteria were ordered in addition to the usual cultures for bacteria and fungi. A tuberculin test was performed at the end of the study. RESULTS: Twenty-eight patients (16 men) with cystic fibrosis were enrolled. The mean (SD) age was 253 (6.7) years. A total of 251 samples were cultured (range in number of samples per patient, 1-31). The mean period of follow up was 40.3 (22.1) months. The sputum smear was positive in 29 cases (4 patients); the culture was positive in 7 patients. More than 3 samples were positive in only 4 patients. Mycobacterium abscessus was isolated in 3 cases, Mycobacterium avium complex in 2 and Mycobacterium simiae in 1 and other an unidentified rapid growth Mycobacterium species. The Mantoux test was positive in 5 patients. Two of the 4 patients in whose samples mycobacteria were isolated repeatedly required treatment. CONCLUSIONS: The prevalence of nontuberculous mycobacterial infection is high in patients with cystic fibrosis. Staining and culture for mycobacteria should be carried out regularly and whenever exacerbation of pulmonary symptoms cannot be attributed to bacteria usually found in such patients. Patients with recurrent isolations of mycobacteria should be monitored closely.