In vitro synergism of colistin in combination with N-acetylcysteine against Acinetobacter baumannii grown in planktonic phase and in biofilms.

S Pollini, S Boncompagni, Maggio T Di, Pilato V Di, T Spanu, B Fiori, F Blasi, S Aliberti, F Sergio, Rossolini GM, L Pallecchi*

*Autore corrispondente per questo lavoro

Risultato della ricerca: Contributo in rivistaArticolopeer review

4 Citazioni (Scopus)

Abstract

OBJECTIVES:\r\nTo investigate the potential synergism of colistin in combination with N-acetylcysteine against Acinetobacter baumannii strains grown in planktonic phase or as biofilms.\r\n\r\nMETHODS:\r\nSixteen strains were investigated, including nine colistin-susceptible (MIC range 0.5-1 mg/L) and seven colistin-resistant (MIC range 16-256 mg/L) strains. Synergism of colistin in combination with N-acetylcysteine was investigated by chequerboard assays. The activity of colistin/N-acetylcysteine combinations was further evaluated by time-kill assays with planktonic cultures (three colistin-resistant strains and one colistin-susceptible strain) and by in vitro biofilm models (three colistin-resistant and three colistin-susceptible strains).\r\n\r\nRESULTS:\r\nChequerboard assays revealed a relevant synergism of colistin/N-acetylcysteine combinations with all colistin-resistant strains, whereas no synergism was observed with colistin-susceptible strains. Time-kill assays showed a concentration-dependent potentiation of colistin activity by N-acetylcysteine against colistin-resistant strains, with eradication of the culture by combinations of N-acetylcysteine at 8000 mg/L plus colistin at 2 or 8 mg/L. A static effect during the first 8 h of incubation was demonstrated with the colistin-susceptible strain exposed to 0.25 × MIC colistin plus 8000 mg/L N-acetylcysteine. A remarkable antibiofilm synergistic activity of 8 mg/L colistin plus 8000 mg/L N-acetylcysteine was demonstrated with all colistin-resistant and colistin-susceptible strains. The effects were greater with colistin-resistant strains (marked reduction of viable biofilm cells was observed at sub-MIC colistin concentrations).\r\n\r\nCONCLUSIONS:\r\nN-acetylcysteine, at concentrations achievable by topical administration, was shown to revert the colistin-resistant phenotype in A. baumannii, and to exert a relevant activity against biofilms of colistin-susceptible and colistin-resistant A. baumannii strains.
Lingua originaleInglese
pagine (da-a)N/A-N/A
Numero di pagine8
RivistaJournal of Antimicrobial Chemotherapy
Numero di pubblicazione72
DOI
Stato di pubblicazionePubblicato - 2018
Pubblicato esternamente

All Science Journal Classification (ASJC) codes

  • Farmacologia
  • Microbiologia (medica)
  • Farmacologia (medica)
  • Malattie Infettive

Keywords

  • Acinetobacter baumannii
  • In vitro synergism

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