Non-tuberculous mycobacteria in children with cystic fibrosis: isolation, prevalence, and predictors.

Background: Screening for non-tuberculous mycobacteria (NTM) is recommended for adults with cystic fibrosis (CF). The relevance of this organism in North American pediatric CF patients is unclear as there is limited NTM prevalence data for children. We aimed to determine the prevalence of NTM in children with CF from a single expectorated sputum and identify clinical predictors of NTM isolation. Additionally, we compared two different sputum decontamination methods before mycobacterial culture.

Methods: From March to November 2004, all sputum-producing patients aged 6-18 years attending the CF clinic at the Hospital for Sick Children in Toronto, Canada, were screened for NTM. Sputum samples were processed by both a single (N-acetyl-l-cysteine + NaOH) and double (N-acetyl-l-cysteine + NaOH + oxalic Acid) decontamination method. Using our CF clinic database and patient charts we analyzed differences in FEV(1), age, sex, pancreatic sufficiency, body mass index, bacterial colonization, and antibiotic use between NTM positive and negative patients.

Results: Of 98 study patients, 6 (6.1%) were positive for NTM, 2 with Mycobacterium abscessus, and 4 with Mycobacterium avium complex. One patient with M. abscessus had clinically significant lung disease requiring treatment. We found no predictors of NTM isolation. The double decontamination method allowed detection of only half (3/6) of the positive NTM cultures.

Conclusions: As the NTM prevalence rate in children with CF is within the range previously reported in adults and there are no reliable clinical predictors for isolation, annual sputum screening is needed to identify NTM in children. Further research is needed to determine the best sputum decontamination method for NTM culture in pediatric patients.