Primary bacterial contamination of wound track.

Forty-four dogs were used. In experimental animals, Serratia marcescens inoculated cloth were placed on the entrance or exist side before shooting, while in control animals no inoculated cloth was placed. Bullet wounding was carried out to both hind legs from a distance of 20 metres. 5.56 mm calibre bullet was used. The impact velocity was 919 m/s or 716 m/s. Bacteriological examination was made immediately or 6 hrs after the shot. The experimental studies showed that primary bacterial contamination of bullet wounds could be resulted immediately after the shot. And it has been verified that the main mechanisms of primary bacterial contamination were two: (1) The bacteria were sucked into the wound by negative pressure of the temporary cavity at both entrance and exit sides. (2) At entrance side, in addition, bacteria could be further carried into the wound tract by contaminated bullet itself.