Isolation of Enterobacteriaceae in airway samples is associated with worse outcome in preschool children with cystic fibrosis

Background: Increased abundance of Enterobacteriaceae(EB) in the respiratory microbiome of young CF patients was reported to precede Pseudomonas aeruginosa(PA) colonisation. We explored whether impending PA colonisation can be predicted by growth of EB in routine airway cultures and whether EB contribute to CF lung disease severity. Methods: We retrospectively studied the records of 62 children with CF for growth of EB and PA during the first 5 years of life and subsequent best lung function at ages 5-7 and 9-11 years. Results: At least one EB positive month occurred in 36/62 (58%) patients. Median (IQR) age at first EB isolation was 0.4 (0.2-0.8) years. PA isolation before age 5 was more frequent in the EB positive (23/36, 54%) than in EB negative children (10/26, 38%; p = 0.048). EB isolation preceded PA isolation in 19/23 (83%) cases (p = 0.003). Median (IQRf) FEV1 at age 5 to 7 years was 105% (94-117) in the EB positive group and 108% (102-115) in the EB negative group (p = 0.154). At age 9-11, FEV1 was lower in EB positive children (99%(88-105) vs 105%(96-110); p = 0.035). Only PA isolation (p = 0.002) before age 5 years was a significant predictor of FEV1 at age 5-7 years. Both EB isolation (p = 0.033) and PA isolation (p = 0.023) were predictors of the FEV1 at age 9-11 years. Conclusion: In preschool children with CF, EB were isolated in just over half of the children. In that subgroup PA isolation was more common. Both EB and PA isolation are associated with worse lung function at later age. (C) 2019 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.