title: In vitro activity of colistin against biofilm by Pseudomonas aeruginosa is significantly improved under "cystic fibrosis-like" physicochemical conditions.
abstract: 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 4 μg/mL, respectively) and biofilm (MBEC90: 512 and 1.024 μg/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.
authors.affiliation: Department of Medical, Oral and Biotechnological Sciences, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, 66100 Chieti, Italy; Center of Excellence on Ageing, "G. d'Annunzio" University Foundation, Via L. Polacchi 11, 66100 Chieti, Italy.
authors.forename: Arianna
authors.initials: A
authors.lastname: Pompilio
authors.affiliation: Department of Medical, Oral and Biotechnological Sciences, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, 66100 Chieti, Italy; Center of Excellence on Ageing, "G. d'Annunzio" University Foundation, Via L. Polacchi 11, 66100 Chieti, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Crocetta
authors.affiliation: Department of Medical, Oral and Biotechnological Sciences, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, 66100 Chieti, Italy; Center of Excellence on Ageing, "G. d'Annunzio" University Foundation, Via L. Polacchi 11, 66100 Chieti, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Pomponio
authors.affiliation: "Bambino Gesù" Children's Hospital, IRCCS, Piazza Sant'Onofrio 4, 00165 Rome, Italy.
authors.forename: Ersilia
authors.initials: E
authors.lastname: Fiscarelli
authors.affiliation: Department of Medical, Oral and Biotechnological Sciences, "G. d'Annunzio" University of Chieti-Pescara, Via dei Vestini 31, 66100 Chieti, Italy; Center of Excellence on Ageing, "G. d'Annunzio" University Foundation, Via L. Polacchi 11, 66100 Chieti, Italy. Electronic address: gdibonaventura@unich.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Di Bonaventura
mesh_terms: D000693:Anaerobiosis; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D003091:Colistin / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry*; D003550:Cystic Fibrosis / Q000150:complications; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests / Q000379:methods*; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D003091:Colistin
keywords: Biofilm; Colistin; Cystic fibrosis; In vitro antimicrobial susceptibility assay; Lung infection; Pseudomonas aeruginosa