Full-thickness porcine burns infected with Staphylococcus aureus or Pseudomonas aeruginosa can be effectively treated with topical antibiotics.

Abstract

Burn and blast injuries are frequently complicated by invasive infections, which lead to poor wound healing, delay in treatment, disability, or death. Traditional approach centers on early debridement, fluid resuscitation, and adjunct intravenous antibiotics. These modalities often prove inadequate in burns, where compromised local vasculature limits the tissue penetration of systemic antibiotics. Here, we demonstrate the treatment of infected burns with topical delivery of ultrahigh concentrations of antibiotics. Standardized burns were inoculated with Staphylococcus aureus or Pseudomonas aeruginosa. After debridement, burns were treated with either gentamicin (2 mg/mL) or minocycline (1 mg/mL) at concentrations greater than 1,000 times the minimum inhibitory concentration. Amount of bacteria was quantified in tissue biopsies and wound fluid following treatment. After six days of gentamicin or minocycline treatment, S. aureus counts decreased from 4.2 to 0.31 and 0.72 log CFU/g in tissue, respectively. Similarly, P. aeruginosa counts decreased from 2.5 to 0.0 and 1.5 log CFU/g in tissue, respectively. Counts of both S. aureus and P. aeruginosa remained at a baseline of 0.0 log CFU/mL in wound fluid for both treatment groups. The findings here demonstrate that super-therapeutic concentrations of antibiotics delivered topically can rapidly reduce bacterial counts in infected full-thickness porcine burns. This treatment approach may aid wound bed preparation and accelerate time to grafting.