Protective effects of the combination of α-helical antimicrobial peptides and rifampicin in three rat models of Pseudomonas aeruginosa infection

Oscar Cirioni, Carmela Silvestri, Roberto Ghiselli, Fiorenza Orlando, Alessandra Riva, Federico Mocchegiani, Leonardo Chiodi, Sefora Castelletti, Eleonora Gabrielli, Vittorio Saba, Giorgio Scalise, Andrea Giacometti

Research output: Contribution to journalArticlepeer-review


Introduction: An experimental study has been performed to compare the in vitro activity and the in vivo efficacy of magainin II and cecropin A with or without rifampicin against control and multidrug-resistant Pseudomonas aeruginosa strains. Methods: In vitro experiments included MIC determinations and synergy studies. For in vivo studies, animals were given an intraperitoneal injection of P. aeruginosa lipopolysaccharide, P. aeruginosa ATCC 27853 and one clinical multiresistant P. aeruginosa strain. Groups of animals received intravenously isotonic sodium chloride solution, 10 mg/kg rifampicin, 1 mg/kg magainin II or 1 mg/kg cecropin A. Two groups of animals received a combined treatment with magainin II + rifampicin or cecropin A + rifampicin at the same dosages as the singly treated groups. In addition, a further group was treated with tazobactam/ piperacillin (120 mg/kg). Lethality, bacterial growth in blood and peritoneum, and endotoxin and TNF-α concentrations in plasma were evaluated. Results: Combinations of α-helical antimicrobial peptides showed in vitro synergistic interaction. Magainin II and cecropin A exerted strong antimicrobial activity and achieved a significant reduction in plasma endotoxin and TNF-α concentrations when compared with control and rifampicin-treated groups. Rifampicin exhibited no anti- P. aeruginosa activity and good substantial impact on endotoxin and TNF-α plasma concentrations. Combined treatment groups had significant reductions in bacterial count, positive blood cultures and mortality rates when compared with singly treated and control groups. Conclusions: Our results highlight the potential usefulness of these combinations that provide future therapeutic alternatives in P. aeruginosa infections.

Original languageEnglish
Pages (from-to)1332-1338
Number of pages7
JournalJournal of Antimicrobial Chemotherapy
Issue number6
Publication statusPublished - 2008


  • Animal model
  • Multiresistant organisms
  • P. aeruginosa
  • Sepsis
  • Synergy

ASJC Scopus subject areas

  • Infectious Diseases
  • Pharmacology (medical)
  • Pharmacology


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