Is the type of chronic pulmonary infection a determinant of lung function outcomes in adult patients with cystic fibrosis?

Background and Aim. Lung function abnormalities are the main factors responsible for the high mortality of cystic fibrosis (CF) patients. It is not yet clear whether Burkholderia cepacia infection causes more pronounced loss of lung function than Pseudomonas aeruginosa infection. Our primary objective was to compare the lung function of adult CF patients with different chronic pulmonary infections. Our second objective was to compare the microbiology using patients’ genetic status. Methods. Fifty-two adult CF patients were divided into 3 groups according to their chronic pulmonary infection profile. All subjects underwent clinical evaluation, pulmonary function tests (PFT) and genetic analysis. Results. The PFT parameters of chronically infected patients were significantly different from those of subjects without pulmonary infection (p < 0.0001). FVC was significantly more altered in patients infected with B. cepacia complex (p < 0.0001); in contrast, FEF25-75% was significantly more altered in patients with P. aeruginosa infection (p < 0.0001). In the groups with chronic P. aeruginosa infection and chronic B. cepacia complex infection, 58.1% and 10% of patients were homozygous for ΔF508, respectively. In addition to chronic infections, pancreatic insufficiency was also associated with lung function deterioration. Conclusion. Chronic pulmonary infection and pancreatic insufficiency are critical processes in lung function deterioration in adult CF patients. Although chronic B. cepacia complex infection causes a more pronounced lung volume reduction, chronic P. aeruginosa infection causes a more pronounced obstruction of small airways. Our results also suggest that ΔF508-homozygous patients are more susceptible to chronic P. aeruginosa infection.