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

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