Assessment of stability and fluctuations of cultured lower airway bacterial communities in people with cystic fibrosis

J Cyst Fibros. 2019 Nov;18(6):808-816. doi: 10.1016/j.jcf.2019.02.012. Epub 2019 Mar 21.

Abstract

Background: Routine clinical culture detects a subset of the cystic fibrosis (CF) airways microbiota based on culture-independent (molecular) methods. This study aimed to determine how extended sputum culture of viable bacteria changes over time in relation to clinical status and predicts exacerbations.

Methods: Sputa from patients at a baseline stable and up to three subsequent time-points were analysed by extended-quantitative culture; aerobe/anaerobe densities, ecological indexes and community structure were assessed together with clinical outcomes.

Results: Eighty patients were prospectively recruited. Sputa were successfully collected and cultured at 199/267 (74.5%) study visits. Eighty-two sputa from 25 patients comprised a complete sample-set for longitudinal analyses. Bacterial density, ecological indexes and clinical outcomes were unchanged in 18 patients with three sequential stable visits. Conversely, in 7 patients who had an exacerbation, total bacterial and aerobe densities differed over four study visits (P < .001) with this difference particularly apparent between the baseline visit and completion of acute antibiotic treatment where a decrease in density was observed. Bacterial communities were more similar within than between patients but stable patients had the least variation in community structure over time. Using logistic regression in a further analysis, baseline features in 37 patients without compared to 15 patients with a subsequent exacerbation showed that clinical measures rather than bacterial density or ecological indexes were independent predictors of an exacerbation.

Conclusions: Greater fluctuation in the viable bacterial community during treatment of an exacerbation than between stable visits was observed. Extended-quantitative culture did not provide prognostic information of a future exacerbation.

Keywords: Bacterial density; Bacterial ecology; Extended-quantitative culture; Sputum.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Anti-Bacterial Agents / therapeutic use*
  • Biota / drug effects*
  • Child
  • Colony Count, Microbial / methods*
  • Cystic Fibrosis* / diagnosis
  • Cystic Fibrosis* / drug therapy
  • Cystic Fibrosis* / microbiology
  • Disease Progression
  • Female
  • Humans
  • Lung / microbiology
  • Male
  • Microbiota / drug effects*
  • Patient Acuity
  • Prognosis
  • Sputum / microbiology*
  • Symptom Assessment* / methods
  • Symptom Assessment* / statistics & numerical data
  • Symptom Flare Up

Substances

  • Anti-Bacterial Agents