A Novel Foam-Forming Hydrogel Containing Antibiotics Reduces the Degree of Bacterial Colonization and Improves Wound Healing in Thermal Burns When Compared to Silver Sulfadiazine.

INTRODUCTION: This study compared a novel antibiotic hydrogel burn dressing to non-antibiotic hydrogel vehicle, standard of care (silver sulfadiazine), and untreated control in a 7-day porcine partial-thickness (second-degree) thermal burn model to assess for wound healing properties both in the presence and absence of bacterial inoculation. MATERIALS AND METHODS: Nineteen swine were enrolled and 18 completed Day 7 analysis. One was euthanized on Day 6 because of an unrelated injury. Eight burn wounds were created on each swine, with half of the wounds inoculated with Staphylococcus aureus and Pseudomonas aeruginosa. Wound treatment was randomized to 4 groups: foam-based hydrogel spray containing antibiotics (i.e., vancomycin and tobramycin), the same hydrogel vehicle without antibiotics, silver sulfadiazine, and no intervention. Observations and primary and secondary outcomes were assessed only on Day 7. A blinded pathologist graded the specimens for bacterial colonization and wound healing. RESULTS: The antibiotic hydrogel demonstrated significantly less bacterial colonization when compared to hydrogel vehicle, silver sulfadiazine, and control (odds ratios of 0.02, 0.02, and 0.01, respectively). The antibiotic hydrogel also demonstrated statistically significant benefits to wound healing when compared to hydrogel vehicle, silver sulfadiazine, and control. Wound healing parameters were factors of histopathology: necrosis depth/length, ulceration, neutrophilic/granulocytic infiltrate, subcutis granulocytic/lymphocytic infiltrates, subcutis fibrosis, congestion, hemorrhage, and edema. CONCLUSIONS: In a 7-day porcine partial thickness burn model, an antibiotic hydrogel foam reduced the degree of bacterial colonization and improved wound healing when compared to non-antibiotic hydrogel vehicle, standard of care, and control. Strengths of this study include the randomization of multiple treatment conditions, blinded pathology, and the inclusion of both inoculated and non-inoculated wounds with clinically relevant bacterial strains. Limitations include a modest sample size and limited quantitative bacteriology. A lightweight, portable foam-based antibiotic hydrogel spray may improve the early, prehospital treatment of thermal burns. Future work may assess use over longer time periods and body surface areas and increased quantitative microbiology.