Spherical steel bullets (0.88 g, 6.00 mm in diameter, impact velocity around 1000 m/s, smooth-bore rifle) were used for infliction of trauma to the thigh of pigs. The aim was to find out the effect of early antibiotic therapy (benzyl-penicillin) on wound infection rate and on the local progressive tissue devitalization when debridement was delayed until 12 hours after infliction of trauma. The main study on infection and tissue devitalization contained 20 missile wounds; the pilot study on cell metabolism 13 wounds. In the first group 11 pigs, and in the second group 7 pigs were treated with penicillin. Debridement was performed 12 hours after the infliction of trauma. Bacteriological analyses were done on tissue samples from the wound after pc treatment. The contents of adenosine triphosphate, creatine phosphate, glucose, glucose 6-phosphate and lactate were analysed in tissue samples from the wound with and without pc-treatment 12 h after trauma. The usual growth of bacteria when debridement was delayed for 12 h was totally inhibited by the early provision of penicillin. The amount of devitalized tissue-removed in relation to transferred energy was significantly reduced after the treatment as compared to the non-pc-group. The results of the studies on cell metabolism point to a graded tissue damage and possibly reversible injuries in the periphery of the wound, and to less metabolic disturbances after pc-treatment. The results indicated that early general supply of antibiotics may confine the local tissue injury when delayed debridement is anticipated.

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.