Background: Ballistics gelatin is a common tissue surrogate used in bacterial contamination models for projectile wounds. Although these studies have demonstrated that bacteria are transferred from the surface of the gelatin to the wound track by a projectile

quantifiable results have been inconsistent and not repeatable in successive tests.Methods: In this study

five areas of a typical contamination model in which bacterial recovery or survival are affected were identified for optimization. The first was a contaminated "skin" surrogate

where the novel use of vacuum filtration of a bacterial culture and buffer onto filter paper was employed. The other possibly problematic areas of the bacterial distribution model included the determination of bacterial survival when the contamination model is dried

survival in solid and molten gelatin

and the effect of high-intensity lights used for recording high-speed video.Results: Vacuum filtration of bacteria and buffer resulted in a consistent bacterial distribution and recovery. The use of phosphate buffer M9（pH 7） aided in neutralizing the ballistics gelatin and improving bacterial survival in solid gelatin. Additionally

the use of high-intensity lights to record high-speed video and the use of a 42℃ water bath to melt the gelatin were found to be bactericidal for gram-positive and gram-negative bacteria.Conclusion: Multiple areas of a typical contamination model in which bacterial survival may be impeded were identified

and methods were proposed to improve survival in each area. These methods may be used to optimize the results of bacterial contamination models for medical applications

such as understanding the progression of infection in penetrating wounds and to identify possible sources of contamination for forensic purposes.