Bacteriological findings in the first 12 hours following experimental missile trauma

The purpose of this study was to investigate the rate and magnitude of bacterial growth in gunshot wounds following debridement one, 6 and 12 hours after infliction of a standardized missile trauma (spherical steel bullet, 0.88 g, 6.00 mm in diameter, impact velocity 1 000 m/sec). 39 pigs were shot in one or both thighs (n of wound, 54). The skin was not cleaned before the trauma but was disinfected preoperatively. Before trauma infliction, swab samples were taken from the nose, the rectum and the skin. At the operation, all muscle tissue judged to be devitalized was removed. Samples for bacteriological culturing were taken from the removed tissue and from the margins of the wound cavity. Isolated bacterial strains were classified and a semiquantitative evaluation of the number of, bacteria was performed. Bacterial growth in the devitalized tissue was indicated in about 70% of the wounds. Cultures from tissue judged as viable and left in the wound indicated contamination in 25% of the wounds in the 1-hour group, contamination in 37 and infection in 11% of the 6-hour group, and in the 12-hour group infection in 60 and contamination in 33%. The conclusion is that wound infection can be overcome by adequate surgical treatment within 6 hours but will be out of control after 12 hours' delay. Furthermore, the results indicate that the presence of a sparse mixed flora probably creates the necessary conditions for infection with other pathogenic strains.