Efficacy of the bovine antimicrobial peptide indolicidin combined with piperacillin/tazobactam in experimental rat models of polymicrobial peritonitis

OBJECTIVE: To investigate the efficacy of piperacillin/tazobactam combined with indolicidin in the prevention of lethality in two rat models of polymicrobial peritonitis. DESIGN: Prospective, randomized, controlled animal study. SETTING: Research laboratory in a university hospital. SUBJECTS: Adult male Wistar rats. INTERVENTIONS: Adult male Wistar rats were given an intraperitoneal injection of 1 mg of Escherichia coli 0111:B4 lipopolysaccharide or had intraabdominal sepsis induced by cecal ligation and puncture. For each model, all animals were randomized to receive isotonic sodium chloride solution intraperitoneally, 1 mg/kg indolicidin, 120 mg/kg piperacillin/tazobactam, and 1 mg/kg indolicidin combined with 120 mg/kg piperacillin/tazobactam. Each group included 20 animals. MEASUREMENTS AND MAIN RESULTS: Main outcome measures were: bacterial growth in blood, peritoneum, spleen, liver, and mesenteric lymph nodes; endotoxin, interleukin-6, and tumor necrosis factor-α concentrations in plasma; and lethality. All compounds reduced significantly bacterial growth and lethality compared with saline treatment. Treatment with indolicidin resulted in significant decrease in plasma endotoxin and cytokine levels, whereas piperacillin/tazobactam exerted the opposite effect. The combination between indolicidin and piperacillin/tazobactam proved to be the most effective treatment in reducing all variables measured. CONCLUSION: Indolicidin may have potential therapeutic usefulness alone and when associated with piperacillin/tazobactam in polymicrobial peritonitis.