In vitro susceptibility ofTrichophyton rubrum isolates to griseofulvin and tioconazole. Induction and isolation of a resistant mutant to both antimycotic drugs

Abstract
The in vitro susceptibility of three clinicalTrichophyton rubrum isolates to griseofulvin and tioconazole, determined by the minimal inhibitory concentration (MIC), was 2 and 0.5 to 1.0μg/ml, respectively. One mutant (gril) obtained after mutagenic treatment of one of these isolates was selected and showed simultaneous resistance to griseofulvin (MIC > 2000μg/ml) and tioconazole (MIC=1.0μg/ml). The clinical importance and the possibility of a multidrug resistance (MDR)-type mechanism being involved in this event is discussed.