title: Inflammatory responses to individual microorganisms in the lungs of children with cystic fibrosis.
abstract: BACKGROUND
  We hypothesized that the inflammatory response in the lungs of children with cystic fibrosis (CF) would vary with the type of infecting organism, being greatest with Pseudomonas aeruginosa and Staphylococcus aureus.
  
  
  METHODS
  A microbiological surveillance program based on annual bronchoalveolar lavage (BAL) collected fluid for culture and assessment of inflammation was conducted. Primary analyses compared inflammation in samples that grew a single organism with uninfected samples in cross-sectional and longitudinal analyses.
  
  
  RESULTS
  Results were available for 653 samples from 215 children with CF aged 24 days to 7 years. A single agent was associated with pulmonary infection (≥10(5) cfu/mL) in 67 BAL samples, with P. aeruginosa (n = 25), S. aureus (n = 17), and Aspergillus species (n = 19) being the most common. These microorganisms were associated with increased levels of inflammation, with P. aeruginosa being the most proinflammatory. Mixed oral flora (MOF) alone was isolated from 165 BAL samples from 112 patients, with 97 of these samples having a bacterial density ≥10(5) cfu/mL, and was associated with increased pulmonary inflammation (P < .001). For patients with current, but not past, infections there was an association with a greater inflammatory response, compared with those who were never infected (P < .05). However, previous infection with S. aureus was associated with a greater inflammatory response in subsequent BAL.
  
  
  CONCLUSIONS
  Pulmonary infection with P. aeruginosa, S. aureus, or Aspergillus species and growth of MOF was associated with significant inflammatory responses in young children with CF. Our data support the use of specific surveillance and eradication programs for these organisms. The inflammatory response to MOF requires additional investigation.
authors.affiliation: Telethon Institute for Child Health Research and the Centre for Child Health Research, University of Western Australia, Perth, Australia.
authors.forename: Catherine
authors.initials: C
authors.lastname: Gangell
authors.forename: Samantha
authors.initials: S
authors.lastname: Gard
authors.forename: Tonia
authors.initials: T
authors.lastname: Douglas
authors.forename: Judy
authors.initials: J
authors.lastname: Park
authors.forename: Nicholas
authors.initials: N
authors.lastname: de Klerk
authors.forename: Tony
authors.initials: T
authors.lastname: Keil
authors.forename: Siobhain
authors.initials: S
authors.lastname: Brennan
authors.forename: Sarath
authors.initials: S
authors.lastname: Ranganathan
authors.forename: Roy
authors.initials: R
authors.lastname: Robins-Browne
authors.forename: Peter D
authors.initials: PD
authors.lastname: Sly
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000472:pathogenicity; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000150:complications / Q000382:microbiology* / Q000473:pathology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007249:Inflammation / Q000382:microbiology* / Q000473:pathology; D008168:Lung / Q000382:microbiology* / Q000473:pathology*; D008297:Male