The contamination of missile wounds with special reference to early antimicrobial therapy

A total number of 64 anesthetized Finnish home bred pigs were wounded in the soft tissue of one thigh. The shooting range was 30 m and 100 m. The weapons were the Finnish M 62, the Russian AKM 47 and the American M 16 A 1. The projectiles were their standard ammunition. Simulating typical field conditions the skin of the pigs was covered by a Finnish field uniform. The skin and the uniform were not cleaned. After trauma the anesthetized pigs were treated in a field hospital and thoroughly examined both clinically and by laboratory tests. Immediately after wounding the wounds were dressed with sterile bandages, which were not touched for 6 hours. Bensyl-penicillin, 300000 units, was administered intravenously to every second pig 1-2 hours after trauma. The wounds were debrided 6 h after wounding and biopsies of devitalized tissue were taken for quantitative bacteriological culture and histological examination. In a group of 12 pigs the specimen was taken 72 h after trauma. After penicillin administration bacterial counts were negative in all wounds but one. No significant contamination was caused by the 7.62 calibre projectiles, but after 6 hours a bacterial count of 102-104/gram of tissue was found in 20% of wounds due to 5.56 calibre shots. The infection was verified histologically. All the wounds in the 723-hour group showed heavy secondary contamination. The study shows that early antimicrobial therapy was useful especially in the case of severe and complicated soft tissue missile wounds in the pigs.