Role of daptomycin on wound healing in a MRSA burn infected animal model.

Prolonged hospitalization and antibiotic therapy are risk factors for the development of methicillin-resistant Staphylococcus aureus (MRSA) infections in thermal burn patients. We used a rat model to study the in vivo efficacy of daptomycin in the treatment of burn wound infections by S. aureus, and we evaluated the wound healing process through morphological and immunohistochemical analysis. A copper bar heated in boiling water was applied on a paraspinal site of each rat, resulting in two full-thickness burns. A small gauze was placed over each burn and inoculated with 5 x 10(7) CFU of S. aureus ATCC 43300. The study included two uninfected control groups with and without daptomycin treatment, an infected control group that did not receive any treatment, and two infected groups treated, respectively, with intraperitoneal daptomycin and teicoplanin. The main outcome measures were quantitative culture, histological evaluation of tissue repair, and immunohistochemical expression of wound healing markers: epidermal growth factor receptor (EGFR) and fibroblast growth factor 2 (FGF-2). The highest inhibition of infection was achieved in the group that received daptomycin, which reduced the bacterial load from 107 CFU/ml to about 103 CFU/g (P < 0.01). The groups treated with daptomycin showed better overall healing with epithelialization and significantly higher collagen scores than the other groups, and these findings were also confirmed by immunohistochemical data. In conclusion, our results support the hypothesis that daptomycin is an important modulator of wound repair by possibly reducing hypertrophic burn scar formation.