Effect of antiseptics, ultraviolet light and lavage on airborne bacteria in a model wound.

We modelled a 'clean' surgical wound lightly contaminated with airborne bacteria, using agar, ovine muscle and ovine adipose tissue. This was used to assess the effect on bacteria of ultraviolet C light (UVC) 1200 mu W/cm2, hydrogen peroxide 3%, povidone-iodine 1% and 10%, chlorhexidine 0.05%, pulsed jet lavage with UVC and syringe and needle lavage with chlorhexidine 0.05%. All the agents were effective on agar, but mixing with blood or plasma neutralised hydrogen peroxide and povidone-iodine 1%. All the agents were less effective on tissue specimens than on agar, but were more effective on adipose tissue than on muscle. All the antiseptics except chlorhexidine were less effective when blood or plasma was added to muscle specimens before disinfection. UVC after pulsed jet lavage had an additive effect. Syringe and needle lavage with chlorhexidine 0.05% was the most effective method tested; it reduced colony counts by 99.8% and warrants clinical investigation.