Predictors of mucoid Pseudomonas colonization in cystic fibrosis patients

Rationale: Chronic mucoid Pseudomonas aeruginosa within the airway in cystic fibrosis (CF) patients can determine prognosis. Understanding the risk factors of mucoid P. aeruginosa acquisition may change how we deliver care. This study aims to evaluate whether presence of risk factors reported to predict disease severity including gender, CFTR genotype, bacterial organisms in airway cultures, and serum levels of vitamins A and E, albumin, C-reactive protein, alpha 1-antitrypsin, and immunoglobulins increased the risk of mucoid P. aeruginosa acquisition. Methods: Primary endpoint was age at first transition from negative to positive culture for mucoid P. aeruginosa. Cox proportional hazards regression with time-dependent covariates examined development of mucoid P. aeruginosa infection and its association with longitudinally measured serum biomarkers, pulmonary function, and culture results for other organisms. Results: Median ages at CF diagnosis and at first culture were 0.55 and 5.7 years, respectively. Median number of cultures/patient was 17. Of the 323 subjects, 150 developed mucoid P. aeruginosa during a median 8.1 years' follow-up. In multivariate analysis, gender (relative hazard [RH] 0.55 for male vs. female, P = 0.001), number of DF508 alleles (RH 1.66 for 1 or 2 vs. 0, P = 0.04), FEV₁ % (RH 1.16 for 10% decrease, P = 0.008), and most recent Staphylococcus aureus status (RH 0.24 for positive vs. negative, P < 0.0001) remained statistically significant. Conclusion: Female gender, number of DF508 alleles, decreased lung function, and lack of S. aureus on recent sputum culture are important risk factors for early detection of mucoid P. aeruginosa.