Upper and lower airway cultures in children with cystic fibrosis: Do not neglect the upper airways

BackgroundAirways of cystic fibrosis (CF) patients are colonised with bacteria early in life. We aimed to analyse differences between results of simultaneously taken upper airway (UAW) and lower airway (LAW) cultures, to describe clinical characteristics of patients with positive versus negative cultures and to follow up the patients with P. aeruginosa positive UAW cultures.MethodsBacteriological and clinical data from 157 children were collected during annual check up. The number of positive UAW and LAW cultures and correspondence between these results and clinical characteristics were analysed.ResultsPositive LAW and UAW cultures were found in 79.6% and 43.9% of patients respectively (p < 0.001). Patients with positive LAW cultures were significantly older (11.9 vs. 9.8 years, p < 0.05) and had more LAW symptoms (73.6% vs. 46.7%, p < 0.05), especially when P. aeruginosa was found. Patients with positive UAW cultures (especially S. aureus) had more nasal discharge (50.7% vs. 25.0%, p < 0.001). In 65% of patients with positive UAW and negative LAW culture for P. aeruginosa the next LAW became P. aeruginosa positive.ConclusionUAW cultures and LAW cultures differ in children with CF and there are differences in clinical characteristics between patients with positive versus negative culture results. P. aeruginosa positive UAW cultures appeared to precede positive LAW cultures in a substantial part of patients, suggesting some kind of cross-infection between the UAW and LAW.