Co-colonisation with Aspergillus fumigatus and Pseudomonas aeruginosa is associated with poorer health in cystic fibrosis patients: An Irish registry analysis

Background: Pulmonary infection is the main cause of death in cystic fibrosis (CF). Aspergillus fumigatus (AF) and Pseudomonas aeruginosa (PA) are the most prevalent fungal and bacterial pathogens isolated from the CF airway, respectively. Our aim was to determine the effect of different colonisation profiles of AF and PA on the clinical status of patients with CF. Methods: A retrospective analysis of data from the Cystic Fibrosis Registry of Ireland from 2013 was performed to determine the effect of intermittent and persistent colonisation with AF or PA or co-colonisation with both microorganisms on clinical outcome measures in patients with CF. Key outcomes measured included forced expiratory volume in one second (FEV₁), number of hospitalisations, respiratory exacerbations and antimicrobials prescribed, and complications of CF, including CF related diabetes (CFRD) and allergic bronchopulmonary aspergillosis (ABPA). Results: The prevalence of AF and PA colonisation were 11% (5% persistent, 6% intermittent) and 31% (19% persistent, 12% intermittent) in the Irish CF population, respectively. Co-colonisation with both pathogens was associated with a 13.8% reduction in FEV₁ (p = 0.016), higher levels of exacerbations (p = 0.042), hospitalisations (p = 0.023) and antimicrobial usage (p = 0.014) compared to non-colonised patients and these clinical outcomes were comparable to those persistently colonised with PA. Intermittent and persistent AF colonisation were not associated with poorer clinical outcomes or ABPA. Patients with persistent PA had a higher prevalence of CFRD diagnosis (p = 0.012). Conclusions: CF patients co-colonised with AF and PA had poor clinical outcomes comparable to patients persistently colonised with PA, emphasising the clinical significance of co-colonisation with these microorganisms.