In vitro activity of climbazole, clotrimazole and silver-sulphadiazine against isolates of Malassezia pachydermatis.

Malassezia pachydermatis is a yeast-like, mainly zoophilic fungus, also known as Malassezia canis. It can be isolated in 20-50% from normal ear cerumen specimen from dogs or cats and has an even higher prevalence in non-suppurative otitis externa in animal species such as these. The genus Malassezia contains the two species M. furfur, a mainly anthropophilic fungus which physiologically occurs on human skin, and M. pachydermatis. We performed Minimal Inhibitory Concentration (MIC)-testings of 40 clinical isolates of M. pachydermatis against climbazole (CLIM), clotrimazole (CLOT) and silver-sulphadiazine (SILV). While CLOT and CLIM are broad-spectrum antimycotics of the azole-type, SILV is a sulphonamide compound with antibacterial and antimycotic properties used topically in veterinary medicine. For CLIM, the range of MICs was between < 0.06 and 1 micrograms/ml with an empirical median mean of 0.06 microgram/ml; for CLOT the range was between < 0.06 and 32 micrograms/ml (mean = 4 micrograms/ml), respectively. The MICs for SILV ranged between 0.25 and > 64 micrograms/ml (mean = 16 micrograms/ml) against all tested strains. In conclusion, the two azole-antimycotics CLIM and CLOT showed good in vitro activity against M. pachydermatis. The activity of CLIM was even higher than that of CLOT, which might be due to the better water solubility of CLIM. The activity of SILV was significantly lower.