Effectiveness of conventional and hydrosurgical debridement methods in reducing Staphylococcus aureus inoculation of equine muscle in vitro

Reasons for performing study: The success of primary healing of equine traumatic wounds is dependent on thorough debridement. A specific hydrosurgical debridement device (Versajet (TM))(a) is gentle to viable tissues, yet effectively removes macroscopic contaminants and debris. We wished to investigate whether it is effective in reducing bacterial burden and whether it differs from traditional methods. No previous reports compare hydrosurgical debridement and conventional wound debridement with regard to bacterial reduction from in vitro inoculated soft tissue.Objectives: To assess the effectiveness of hydrosurgical debridement in reducing the Staphylococcus aureus load from in vitro inoculated equine muscle compared with conventional wound debridement methods.Study design: In vitro experimental study.Methods: The surface of equine masseter muscle was inoculated with a S. aureus broth and subsequently debrided using one of the following 4 methods: saline irrigation; sharp debridement; saline irrigation and sharp debridement; or hydrosurgical debridement. Tissue samples for quantitative cultures were collected before and after debridement, and the colony-forming units per gram of tissue were calculated and log transformed. The reductions in bacterial counts were analysed statistically using Wilcoxon signed-rank tests and Friedman two-way ANOVA.Results: Hydrosurgical debridement was more effective than conventional debridement methods in reducing the S. aureus load (P<0.05). Hydrosurgical debridement reduced the bacterial load by 99.7%, in comparison to saline irrigation and sharp debridement (87.4%), sharp debridement (82.2%) and saline irrigation (46.0%).Conclusions: Hydrosurgical debridement reduces the S. aureus load from in vitro contaminated equine muscle significantly more than conventional debridement methods.