Therapeutic effect of a pig-derived peptide antibiotic on porcine wound infections

Purpose: We investigated the therapeutic potential of the pig-derived antim icrobial peptide protegrin-1 (PG-1) against porcine skin wounds infected wi th Pseudomonas aeruginosa, Materials and Methods: Using a porcine skin wound model, PG-1 was added to the wound fluid either at the time of P, aeruginosa inoculation, four hours after inoculation or 24 hours after inoculation. Wound fluids were analyze d 20-24 hours later by use of colony-forming unit (CFU) assays, semiquantit ative immunoblot analysis for PG-1, and radial diffusion assays (RDA) for r esidual in vitro activity. Results: Results of the CFU assays indicated a 10,000-fold decrease in the number of bacteria when PG-1 was added at the time of inoculation, a 120-fo ld decrease when added 4 hours after inoculation and a 10-fold decrease whe n added 24 hours after inoculation, Results of immunoblot analysis and RDA indicated that PG-1 concentrations for each of the three conditions remaine d increased in wound fluid 20 to 24 hours after treatment, and correlated w ith increased residual in vitro antimicrobial activity. Conclusions: These results document that the endogenous antibiotic PG-1 sig nificantly prevented the colonization of P. aeruginosa in wounds and reduce d the in vivo bacterial concentration in established wound infections. Ther apeutics used in the same animal species from which they were derived are a promising means for preventing and treating localized infections.