From model to molecules: the development and experimental manipulation of an in vivo contaminated extremity war wound

Wound infection is a key determinant of outcome in survivors of armed conflict. One factor having potential for promoting healing, decreasing bacterial burden and influencing prognosis is the dressing that covers the ballistic-injured extremity. Although antiseptic and silver dressings are applied to acute wounds, evidence to support their use is scarce with no controlled studies reported of antimicrobial wound dressings in extremity trauma. Given the recent burden of ballistic extremity injury, the requirement to investigate the role of antimicrobial dressings in contaminated wounds is transparent. This paper details a programme of work undertaken at the Defence Science and Technology Laboratory of developing and trialling a recovery model to investigate the early management of contaminated war wounds. A New Zealand White rabbit flexor carpi ulnaris muscle belly, isolated and then injured by a drop rig mechanism, was contaminated with Staphylococcus aureus to provide a reproducible contaminated muscle wound. This model was developed to support a series of randomised controlled trials to determine the impact of antimicrobial dressings on decreasing the bacterial burden of combat related extremity wounds. The results of the initial trial indicated that over a 48-h period, dressings augmented with antiseptic or silver offer no advantage over saline-soaked gauze in reducing the bacterial burden of a contaminated soft tissue injury. The model has subsequently been used to investigate the efficacy of dressings over a 7-day study period and impact of antibiotics and to evaluate biofilm formation and wound cytokines.