Recovery of lung function following a pulmonary exacerbation in patients with cystic fibrosis and the G551D-CFTR mutation treated with ivacaftor.

BACKGROUND: Pulmonary exacerbations (PEx) are associated with acute loss of lung function that is often not recovered after treatment. We investigated lung function recovery following PEx for ivacaftor- and placebo-treated subjects. METHODS: Short- and long-term pulmonary function recovery data after PEx were summarized from a placebo-controlled trial in 161 cystic fibrosis patients≥12years old with the G551D-CFTR mutation (NCT00909532). Short-term recovery was measured 2 to 8weeks after treatment, and long-term recovery was determined at the end-of-study, both compared with baseline measured just prior to the PEx. RESULTS: Fewer patients receiving ivacaftor experienced a PEx than patients receiving placebo (33.7% vs. 56.4%; P=0.004) and had a lower adjusted incidence rate of PEx (0.589 vs. 1.382; P<0.001). The proportion of PEx followed by full short-term recovery of percent predicted forced expiratory volume in 1s was similar (ivacaftor vs. placebo, 57.1% vs. 53.7), as was the proportion of patients having long-term recovery (46.4% vs. 47.7%). CONCLUSIONS: Ivacaftor treatment reduces the frequency of PEx but does not improve on the rate of complete lung function recovery after PEx when compared with placebo.

Lung microbiota across age and disease stage in cystic fibrosis.

Understanding the significance of bacterial species that colonize and persist in cystic fibrosis (CF) airways requires a detailed examination of bacterial community structure across a broad range of age and disease stage. We used 16S ribosomal RNA sequencing to characterize the lung microbiota in 269 CF patients spanning a 60 year age range, including 76 pediatric samples from patients of age 4-17, and a broad cross-section of disease status to identify features of bacterial community structure and their relationship to disease stage and age. The CF lung microbiota shows significant inter-individual variability in community structure, composition and diversity. The core microbiota consists of five genera - Streptococcus, Prevotella, Rothia, Veillonella and Actinomyces. CF-associated pathogens such as Pseudomonas, Burkholderia, Stenotrophomonas and Achromobacter are less prevalent than core genera, but have a strong tendency to dominate the bacterial community when present. Community diversity and lung function are greatest in patients less than 10 years of age and lower in older age groups, plateauing at approximately age 25. Lower community diversity correlates with worse lung function in a multivariate regression model. Infection by Pseudomonas correlates with age-associated trends in community diversity and lung function.

Phenotypic diversity within a Pseudomonas aeruginosa population infecting an adult with cystic fibrosis.

Chronic airway infections caused by Pseudomonas aeruginosa contribute to the progression of pulmonary disease in individuals with cystic fibrosis (CF). In the setting of CF, within-patient adaptation of a P. aeruginosa strain generates phenotypic diversity that can complicate microbiological analysis of patient samples. We investigated within- and between- sample diversity of 34 phenotypes among 235 P. aeruginosa isolates cultured from sputum samples collected from a single CF patient over the span of one year, and assessed colony morphology as a screening tool for predicting phenotypes, including antimicrobial susceptibilities. We identified 15 distinct colony morphotypes that varied significantly in abundance both within and between sputum samples. Substantial within sample phenotypic heterogeneity was also noted in other phenotypes, with morphotypes being unreliable predictors of antimicrobial susceptibility and other phenotypes. Emergence of isolates with reduced susceptibility to ß-lactams was observed during periods of clinical therapy with aztreonam. Our findings confirm that the P. aeruginosa population in chronic CF lung infections is highly dynamic, and that intra-sample phenotypic diversity is underestimated if only one or few colonies are analyzed per sample.

Incidence and prevalence of diabetes mellitus in patients with cystic fibrosis undergoing lung transplantation before and after lung transplantation.

Cystic fibrosis (CF) related diabetes mellitus (DM) occurs in 15% of adult pancreatic insufficient CF patients. Lung transplantation is a treatment option for end-stage CF. We hypothesized that the prevalence of DM increases after lung transplantation. The study population included adult patients undergoing lung transplantation from March 1988 to March 2002 for end-stage CF at the University of Toronto. Demographic data, exocrine pancreatic function, presence of DM before and after transplant, as well as timing of its development after transplant were collected. Eighty-six patients met the study criteria; 77 of 86 (89.5%) of patients were pancreatic insufficient and were further analyzed. Median follow-up post-transplant was 3.3 yr (interquartile range: 1.2-7.2). Their mean age was 29.7 +/- 8.1 yr and 46 of 77 (59.7%) were male. The prevalence of DM increased from 22 of 77 (28.6%) before transplant to 38 of 77 (49.4%) after transplant (p = 0.008). The median time of DM development after transplant was 80 d (range: 13-4352). Sixteen of 55 (29.1%) of pancreatic insufficient patients who were non-diabetic prior to transplant, developed DM after transplant. DM is common in CF patients undergoing lung transplantation and the prevalence increases after transplant.