Age at acquisition of pulmonary infection and respiratory outcome in cystic fibrosis

Acquisition of P. aeruginosa has been associated with a poor prognosis in people with cystic fibrosis, but this association is less well established in young children. Aim: To examine the impact of age at acquisition of P. aeruginosa and other specific respiratory pathogens on lung function at 6 years. Methods: Children with CF diagnosed on newborn screening in 1990-1992 in Victoria underwent serial bronchoalveolar lavage (BAL) in the first two years of life, usually soon after diagnosis and again at 1 and 2 years. Quantitative microbiology was performed on BAL fluid. Routine spirometry was performed as part of three-monthly review from the age of six years. The best FEV< achieved prior to the 7birthday was recorded as a percent of predicted value. Results: 56 children (26 males) were studied, representing 86% of the 1990-92 birth cohort. 40 had spirometry results available. 20 children (36%) had P. aeruginosa isolated on BAL fluid or sputum prior to the age of six years (mean age at first isolation 33 mo; range 4-72). 4 infants died prior to the age of 6 years (range 4-64 mo). 3 of the children who died had P. aeruginosa cultured from BAL fluid prior to death. P. aeruginosa was cultured from the other infant from post-mortem lung biopsy. 22 children (38%) had Staphylococcus aureus or other pathogens isolated at a mean age of 21 months. No children with negative culture for P. aeruginosa died. The surviving children who had had positive culture for P. aeruginosa had a mean FEVi in the 7 year of life of 93% predicted. This was not significantly different from the groups with S.aureus, other pathogens or negative cultures (mean % predicted FEV. 111,98,107 respectively). Within the P. aeruginosa positive group, there was no correlation between age at first isolation of the organism and FEVi in 7th year. Conclusion: While the culture of P. aeruginosa prior to six years of age was associated with a significantly increased risk of death in this cohort, no association was found between the isolation of this organism and medium term lung function in survivors. Lung function in those with P. aeruginosa was not significantly different from those children infected with other pathogens.