Increasing nontuberculous mycobacteria infection in cystic fibrosis

Nontuberculous mycobacteria (NTM) are emerging infections in the CF population.

To assess NTM infection prevalence and associated features in our CF clinic population.

Patient records, 2002-2011, were reviewed for NTM infection. FEV1, pancreatic function, sputum microbiology, and serum cytokines were compared in patients with and without NTM infection.

Incidence rate of NTM infection increased from 0 in 2002 to 8.7% in 2011 (p<0.001). NTM infection prevalence increased 3-fold from 5% (4/79) in 2003 to 14.5% (16/110) in 2011 (p=0.05). Prevalence of chronic NTM lung disease has decreased somewhat since a peak in 2009, with institution of aggressive triple therapy. Of NTM-infected compared to uninfected patients, 88.2% vs. 60.3% had a known 'severe' CFTR genotype (p=0.04), 88.2% vs. 58.9% were pancreatic insufficient (p=0.02); 70.6% vs. 43.8% had chronic Pseudomonas aeruginosa (p=0.06); 75% vs. 32% had Aspergillus infection (p=0.007) and 23.5% vs 2.7% had allergic bronchopulmonary aspergillosis (p=0.01). Patients infected with Mycobacterium abscessus had increased TGF-β, TNF-α, IL-1β, IL-2, IL-4 and IL-5 levels (p<0.05). There was no difference in cytokine levels for all NTM infected compared to uninfected patients. M. abscessus comprised 46% of all NTM infections. Comparing M. abscessus versus other NTM, duration was 10.5 (1-118) months versus 1 (1-70) month, median (range) (p=0.004); lung disease occurred in 69% versus 17% (p=0.0004), with sputum conversion in 4/11 versus 5/6, respectively (NS).

NTM incidence and prevalence have increased dramatically in our CF clinic, associated with a severe CF genotype and phenotype. M. abscessus, the most prevalent NTM, caused prolonged infection despite therapy. There has been some decrease in the prevalence of NTM lung disease since 2009.