Clinical outcomes associated with Staphylococcus aureus and Pseudomonas aeruginosa airway infections in adult cystic fibrosis patients

Background: Staphylococcus aureus (SA) is the most prevalent organism infecting the respiratory tract of CF children, and remains the second most prevalent organism in CF adults. During early childhood, SA infections are associated with pulmonary inflammation and decline in FEV1, but their clinical significance in adult CF patients is poorly characterized. Methods: We conducted a retrospective cross-sectional study to determine the association between airway microbiology and clinical outcomes (FEV1, rate of pulmonary exacerbations, CRP levels and clinical scores). Results: In a cohort of 84 adult CF patients, 24 % were infected with SA only, 60 % were infected with PA, and 16 % had neither PA nor SA. CF patients with SA experienced fewer pulmonary exacerbations and lower CRP levels than those with PA. Conclusion: In adult CF patients, SA infections alone, in the absence of PA, are a marker of milder disease.