Use of lyophilized skin for testing the bactericidal activity of teat disinfectants

The bactericidal activities of various concentrations of 3 disinfectants commonly used for teat disinfection were compared in vitro using small discs of pig skin previously contaminated with Staphylococcus aureus. Solutions containing 40 g/l Na hypochlorite, 25 or 50 g/l chlorhexidine digluconate or iodophor containing 5 g/l iodine were found to have equivalent or superior bactericidal activity to a solution containing 10 g/l Na hypochlorite. This in vitro technique offers a convenient alternative to in vivo tests for teat disinfectants and with minor modifications could be applicable to the testing of skin antiseptics in general.