title: Does bacterial density in cystic fibrosis sputum increase prior to pulmonary exacerbation?
abstract: BACKGROUND
  Cystic Fibrosis (CF) lung disease is characterised by an inexorable decline in lung function, punctuated by periods of symptomatic worsening known as pulmonary exacerbations (referred to here as CFPE). Despite their clinical significance, the cause of CFPE remains undetermined. It has been suggested that an increase in bacterial density may be a trigger, although this has not been shown empirically.
  
  
  METHODS
  Here, a previously validated quantitative PCR-based approach was used to assess numbers of Pseudomonas aeruginosa and of total bacteria in respiratory secretions from patients during the period leading up to CFPE. Sputum samples collected from 12 adult CF patients were selected retrospectively to fall approximately 21, 14, 7 and 0 days prior to CFPE diagnosis. In addition, the relationships between clinical parameters (FEV(1), temperature and patient reported outcome measures) and microbiological data were investigated.
  
  
  RESULTS
  No significant changes either in total bacterial or P. aeruginosa numbers were identified prior to CFPE. Of all the correlations tested, only temperature showed a significant correlation with total bacterial numbers in the period leading to CFPE.
  
  
  CONCLUSIONS
  These findings strongly suggest that CFPE do not generally result from increased bacterial density within the airways. Instead, data presented here are consistent with alternative models of pulmonary exacerbation.
authors.affiliation: Molecular Microbiology Research Laboratory, Institute of Pharmaceutical Sciences, 150 Stamford Street, Franklin-Wilkins Building, King's College London, London, SE1 9NH, UK.
authors.forename: Franziska A
authors.initials: FA
authors.lastname: Stressmann
authors.forename: Geraint B
authors.initials: GB
authors.lastname: Rogers
authors.forename: Peter
authors.initials: P
authors.lastname: Marsh
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Lilley
authors.forename: Thomas W V
authors.initials: TW
authors.lastname: Daniels
authors.forename: Mary P
authors.initials: MP
authors.lastname: Carroll
authors.forename: Lucas R
authors.initials: LR
authors.lastname: Hoffman
authors.forename: Graeme
authors.initials: G
authors.lastname: Jones
authors.forename: Collette E
authors.initials: CE
authors.lastname: Allen
authors.forename: Nilesh
authors.initials: N
authors.lastname: Patel
authors.forename: Benjamin
authors.initials: B
authors.lastname: Forbes
authors.forename: Andrew
authors.initials: A
authors.lastname: Tuck
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Bruce
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D058491:Bacterial Load; D003550:Cystic Fibrosis / Q000382:microbiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000175:diagnosis / Q000188:drug therapy / Q000382:microbiology* / Q000503:physiopathology; D011552:Pseudomonas Infections / Q000175:diagnosis / Q000188:drug therapy / Q000382:microbiology* / Q000503:physiopathology; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D013183:Sputum / Q000382:microbiology*; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents