Reduced bacterial colony count of anaerobic bacteria is associated with a worsening in lung clearance index and inflammation in cystic fibrosis

PLoS One. 2015 May 20;10(5):e0126980. doi: 10.1371/journal.pone.0126980. eCollection 2015.


Anaerobic bacteria have been identified in abundance in the airways of cystic fibrosis (CF) subjects. The impact their presence and abundance has on lung function and inflammation is unclear. The aim of this study was to investigate the relationship between the colony count of aerobic and anaerobic bacteria, lung clearance index (LCI), spirometry and C-Reactive Protein (CRP) in patients with CF. Sputum and blood were collected from CF patients at a single cross-sectional visit when clinically stable. Community composition and bacterial colony counts were analysed using extended aerobic and anaerobic culture. Patients completed spirometry and a multiple breath washout (MBW) test to obtain LCI. An inverse correlation between colony count of aerobic bacteria (n = 41, r = -0.35; p = 0.02), anaerobic bacteria (n = 41, r = -0.44, p = 0.004) and LCI was observed. There was an inverse correlation between colony count of anaerobic bacteria and CRP (n = 25, r = -0.44, p = 0.03) only. The results of this study demonstrate that a lower colony count of aerobic and anaerobic bacteria correlated with a worse LCI. A lower colony count of anaerobic bacteria also correlated with higher CRP levels. These results indicate that lower abundance of aerobic and anaerobic bacteria may reflect microbiota disruption and disease progression in the CF lung.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use
  • Bacteria, Aerobic / drug effects
  • Bacteria, Anaerobic / cytology*
  • Bacteria, Anaerobic / drug effects
  • Bacterial Load*
  • C-Reactive Protein / metabolism
  • Case-Control Studies
  • Child
  • Cystic Fibrosis / complications*
  • Cystic Fibrosis / microbiology*
  • Female
  • Forced Expiratory Volume / drug effects
  • Humans
  • Inflammation / complications*
  • Inflammation / pathology*
  • Lung / drug effects
  • Lung / microbiology*
  • Lung / pathology
  • Male
  • Microbiota / drug effects
  • Middle Aged
  • Sputum / drug effects
  • Sputum / microbiology
  • Young Adult


  • Anti-Bacterial Agents
  • C-Reactive Protein

Grant support

This work was funded by HSC Research and Development, Public Health Agency, Northern Ireland and the Medical Research Council through a US-Ireland Partnership Grant. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.