title: Upper and lower airway cultures in children with cystic fibrosis: do not neglect the upper airways.
abstract: BACKGROUND
  Airways 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.
  
  
  METHODS
  Bacteriological 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.
  
  
  RESULTS
  Positive 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. 9.8years, 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.
  
  
  CONCLUSIONS
  UAW 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.
authors.affiliation: Department of Paediatric Respiratory Disease, Cystic Fibrosis Centre Utrecht, Wilhelmina Children's Hospital, KH 01.419.0, University Medical Centre Utrecht, PO Box 85090, 3508 AB Utrecht, The Netherlands.
authors.forename: Hilde J C
authors.initials: HJ
authors.lastname: Bonestroo
authors.forename: Karin M
authors.initials: KM
authors.lastname: de Winter-de Groot
authors.forename: Cornelis K
authors.initials: CK
authors.lastname: van der Ent
authors.forename: Hubertus G M
authors.initials: HG
authors.lastname: Arets
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D001419:Bacteria / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003371:Cough / Q000209:etiology; D003550:Cystic Fibrosis / Q000150:complications / Q000378:metabolism / Q000382:microbiology* / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009297:Nasal Mucosa / Q000378:metabolism / Q000382:microbiology*; D009298:Nasal Polyps / Q000209:etiology; D011552:Pseudomonas Infections / Q000175:diagnosis; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D012137:Respiratory System / Q000382:microbiology*; D013183:Sputum / Q000378:metabolism / Q000382:microbiology*; D055815:Young Adult