SUSCEPTIBILITY OF MALASSEZIA-FURFUR SUBGROUPS TO TERBINAFINE

Malassezia furfur, the fungus causing pityriasis versicolor, has been reported to be sensitive to terbinafine in vitro but although topical therapy is effective in the treatment of pityriasis versicolor, oral t herapy is not. This phenomenon was investigated by determining the sus ceptibility to terbinafine of different M. furfur subgroups in vivo (d uring topical or oral application) and in vitro. All M. furfur subgrou ps were suppressed (approximate to 10-fold) by topical terbinafine. Or al treatment resulted in no significant suppression of cutaneous M. fu rfur populations with the exception of a single subgroup (A), which wa s reduced to undetectable levels on the skin of eight of 10 patients r eceiving oral terbinafine. Isolates of subgroup A were also markedly m ore susceptible to terbinafine in laboratory tests. The importance of the recognition of distinct subgroups within the cutaneous lipophilic yeasts when evaluating their antifungal susceptibility and their role in disease is discussed.