Persistent wound infection delays epidermal maturation and increases scarring in thermal burns.

We developed a reliable scale measuring epidermal maturation during wound healing and determined the effects of persistent infection on epidermal maturation and dermal scarring after cutaneous burns. A secondary analysis of data from 80 contaminated burns collected during a randomized experiment comparing four topical burn therapies in a contaminated porcine burn model was performed. Persistent infection was defined histologically as the presence of intradermal neutrophils containing bacteria at 14 days. Epidermal maturation at 14 days was classified into one of five categories from least (0) to most (4) mature using strictly defined criteria. Dermal scarring was classified as none, superficial, or deep. The epidermal classification system was highly reliable (rho = 0.97). At 14 days, 18% of burns were infected. Most infected wounds (79%) had an immature epidermis (types 0-2) while most noninfected wounds (75%) had a mature epidermis (types 3 or 4); chi2 and chi2 for linearity both p < 0.001. Deep scars were more common in infected (93%) than noninfected wounds (29%), p < 0.001. We conclude that our scale is reliable and that persistence of infection 14 days after thermal injury is associated with delayed epidermal maturation and deep scarring.