A Comparison of Antimicrobial Efficacy and Tissue Reaction of Four Antiseptics on Canine Wounds

Three concentrations of povidone iodine, chlorhexidine, benzalkonium chloride, and a pluronic polyol were tested for antimicrobial efficacy and tissue reaction in wounds inoculated with Staphyloccocus aureus .
Five paired incisions were created on the back of each of 16 dogs in four treatment groups. Five wounds were inoculated with beta-hemolytic, coagulase positive S. aureus (10⁹ organisms); the contralateral wounds were not inoculated. After two hours, three wounds on each side were irrigated with antiseptic in low, medium, or high concentrations; another was irrigated with physiological saline; and one was left untreated. One hundred ml of solution was applied in each instance with a syringe and needle at approximately 8 psi.
Tissue bacteria were quantitated immediately following irrigation. The wounds were sutured with 5/0 monofilament stainless steel and bandaged. After 48 hours, the dogs were euthanized and signs of wound infection were recorded. Wound bacteria were quantitated again, and sections of the wounds were removed for examination by light microscopy.
Antiseptics were significantly effective (p < 0.01) in reducing the bacterial population in contaminated wounds when compared to control wounds on the same dog. High antiseptic concentrations were more effective than low concentrations. At 48 hours, the bacterial population was significantly lower in wounds treated with chlorhexidine or benzalkonium chloride compared with povidone iodine or pluronic polyol. The antiseptics caused no significant difference (p < 0.01) in tissue reaction in noninoculated wounds. Chlorhexidine (0.5 or 1.0%) was the most effective antiseptic under the conditions used.