Biomedical Engineering Program, South Dakota School of Mines and Technology, 501 E. Saint Joseph St., Rapid City, SD, 57701, USA.
Mechanical Engineering Department, South Dakota School of Mines and Technology, 501 E. Saint Joseph St., Rapid City, SD, 57701, USA.
Mil Med Res. 2018 May 25;5(1):16. doi: 10.1186/s40779-018-0164-7.
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.
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.
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 42C water bath to melt the gelatin were found to be bactericidal for gram-positive and gram-negative bacteria.
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.
弹道明胶是一种常用的组织替代物，用于弹丸伤口的细菌污染模型。虽然这些研究表明细菌通过弹丸从明胶表面转移到伤口轨迹，但可量化的结果在连续测试中不一致且不可重复。
在这项研究中，确定了影响细菌回收或存活的典型污染模型中的五个区域进行优化。第一个是受污染的“皮肤”替代物，其中采用了将细菌培养物和缓冲液真空过滤到滤纸上的新方法。细菌分布模型中其他可能存在问题的区域包括确定污染模型干燥时细菌的存活情况、固体和熔融明胶中的存活情况，以及用于记录高速视频的高强度灯光的影响。
真空过滤细菌和缓冲液可导致一致的细菌分布和回收。使用磷酸盐缓冲液 M9（pH 7）有助于中和弹道明胶并提高固体明胶中细菌的存活能力。此外，发现使用高强度灯光记录高速视频和使用 42°C 水浴融化明胶对革兰氏阳性菌和革兰氏阴性菌均具有杀菌作用。
确定了典型污染模型中可能阻碍细菌存活的多个区域，并提出了在每个区域提高细菌存活能力的方法。这些方法可用于优化细菌污染模型在医疗应用中的结果，例如了解穿透性伤口感染的进展，并确定法医目的的可能污染源。
