The bactericidal activity of a teat dip containing chlorhexidine and cetrimide.

Using an in vivo test on teat skin the disinfectant activity of a teat dip containing chlorhexidine and cetrimide was compared with two iodophor solutions, one containing the recommended concentration of 0.5 per cent available iodine and the other a 10-fold dilution of this (0.05 per cent iodine). The test organisms used were Staphylococcus aureus and Escherichia coli and for both species the 0.5 per cent iodophor was significantly more bactericidal than either the diluted iodophor or the chlorhexidine/cetrimide teat dip (P less than 0.01). In the test against S aureus, chlorhexidine/cetrimide and the 0.05 per cent iodophor showed similar bactericidal activity, but the iodophor was significantly more bactericidal against E coli (P less than 0.01). It is argued that due to its low bactericidal activity this formulation of chlorhexidine/cetrimide is likely to be inferior to 0.5 per cent iodophor solution as a disinfectant teat dip.