In vitro activity of colistin against biofilm by Pseudomonas aeruginosa is significantly improved under "cystic fibrosis-like" physicochemical conditions

Arianna Pompilio, Valentina Crocetta, Stefano Pomponio, Ersilia Fiscarelli, Giovanni Di Bonaventura

Research output: Contribution to journalArticle


The impact of physicochemical conditions observed in cystic fibrosis (CF) lung on colistin activity against both planktonic and biofilm P. aeruginosa cells was evaluated. MIC, minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) values were assessed against 12 CF strains both under "CF-like" (anaerobiosis, pH6.4) and "standard" (aerobiosis, pH7.4) conditions. The activity of colistin was significantly higher under "CF-like" conditions compared to "standard" ones, both against planktonic (MIC90: 1 and 4μg/mL, respectively) and biofilm (MBEC90: 512 and 1.024μg/mL, respectively) cells, as confirmed by scanning electron microscopy. Improved activity was not related to biofilm matrix amount. It may be necessary to adequately "rethink" the protocols used for in vitro assessment of colistin activity, by considering physicochemical and microbiological features in the CF lung at the site of infection. This could provide a more favorable therapeutic index, rationale for administration of lower doses, probably resulting in reduced toxicity and emergence of resistant clones.

Original languageEnglish
Pages (from-to)318-325
Number of pages8
JournalDiagnostic Microbiology and Infectious Disease
Issue number4
Publication statusPublished - Aug 1 2015



  • Biofilm
  • Colistin
  • Cystic fibrosis
  • In vitro antimicrobial susceptibility assay
  • Lung infection
  • Pseudomonas aeruginosa

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases

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