Effect of plastic skin and wound drapes on the density of bacteria in operation wounds.

Operation wounds were sampled quantitatively by the velvet pad rinse technique to determine the effect of impervious plastic skin and wound drapes on the density of bacteria. A controlled trial (clean operations) revealed no significant difference between the bacterial density of herniotomy wounds for which the skin had been covered with adhesive plastic drapes, and the bacterial density of wounds in which skin drapes had not been used. The bacterial density in the wounds did not differ significantly from that on the adjacent skin; both densities were slightly higher at the end of operation than at the beginning. Within the operation wound, sites of low bacterial density were close to sites with a high density. Staphylococcus epidermidis predominated, while Staphylococcus aureus occurred only once; intestinal species were not isolated. In another controlled trial (potentially contaminated operations) plastic wound drapes gave an equally high reduction in bacterial density before closure of laparotomy wounds after either truncal vagotomy and pyloroplasty or gastric and colorectal operations. The reduction in the density of intestinal species was close to 100 per cent and did not differ significantly from that of alpha-haemolytic streptococci, the density of this species being significantly more reduced than that of staphylococci, diphteroids and bacilli. It is concluded that plastic skin drapes were without influence on the species and density of bacteria in operation wounds. Plastic wound drapes, on the other hand, considerably reduced not only exogenous but in particular endogenous bacteria, which otherwise would have remained in the operation wounds.