The effects of an occlusive zinc medicated dressing on the bacterial flora in excised wounds in the rat.

The effects of three different dressings - two occlusive and one non-occlusive - on the bacterial flora of excised wounds in rats were studied. The number of colony forming units per gram of granulation tissue were significantly lower 4, 8 and 12 days postoperatively in wounds treated with a zinc medicated occlusive dressing compared with wounds treated with non-zinc medicated occlusive hydrocolloid dressing or wet-to-dry non-occlusive gauze dressing. The minimum inhibitory concentration (MIC) of zinc sulphate was determined on different strains of bacteria isolated from the wounds of rats and on strains isolated from humans. The most susceptible species isolated from both rat wounds and humans were Streptococcus sp., STaphylococcus aureus and Escherichia coli; whereas, Proteus and Enterococcus sp. had higher MIC-values. In vitro, the hydrocolloid dressing disclosed no antibacterial effects. If the practitioner prefers an occlusive dressing we believe, due to our animal and in vitro experiments, that the zinc medicated occlusive dressing will reduce the risk of wound infection in man.