Synergistic inhibition of the growth in vitro of Microsporum canis by miconazole and chlorhexidine

An agar dilution technique was used to assess the minimum inhibitory concentrations (MIC) of miconazole, chlorhexidine and a 1:1 combination of both agents for 10 isolates of Microsporum canis. For nine of 10 of the isolates, a combination of miconazole and chlorhexidine was more effective than either agent alone; fractional inhibitory concentration indices indicated a synergistic effect for five isolates and an additive effect for four. These results illustrate the potent antimycotic effect of miconazole and chlorhexidine against M. canis and are in accordance with previous clinical studies that showed the value of using miconazole and chlorhexidine shampoo in association with oral griseofulvin in the treatment of feline dermatophytosis caused by M. canis.