Nontuberculous mycobacterial infection in young children with cystic fibrosis

Although nontuberculous mycobacteria (NTM) are recognized pathogens in adolescent and adult patients with cystic fibrosis (CF), the role of NTM in younger CF patients is not well-defined. To explore NTM infection in CF patients less than 12 years old, a retrospective review was performed. Prevalence was estimated from routine mycobacterial cultures of bronchoalveolar lavage (BAL) specimens collected over a 3-year period. NTM-positive cultures were obtained from 9 of 258 BALs collected from 7 of 114 different patients (5 months to 11 years of age). Further data were acquired from microbiological and clinical records of all pediatric patients with CF over a 10-year period. A total of 17 patients had at least one positive mycobacterial culture at less than 12 years of age, 5 of whom had positive cultures before age 5. The most commonly identified organisms were Mycobacterium avium-complex and Mycobacterium abscessus. Of the 17 patients, 10 met American Thoracic Society (ATS) microbiological criteria for mycobacterial disease, and 7 did not. The two groups did not differ with respect to age, gender, or presence of other respiratory pathogens. Patients who met ATS microbiological criteria for disease were more likely to have positive smears for acid-fast bacilli and grow Mycobacterium abscessus from culture. These patients also had a greater decline in lung function over time than patients who did not meet the microbiologic criteria. These data suggest that NTM represent a clinically significant pathogen, even in young patients with cystic fibrosis.