In vitro activity of voriconazole against dermatophytes, Scopulariopsis brevicaulis and other opportunistic fungi as agents of onychomycosis

Using a reference microdilution method, we studied the antifungal susceptibility to voriconazole and fluconazole of 304 clinical isolates from four species of onychomycosis-causing dermatophytes, 196 isolates of dermatophytes not related to nail infection as well as Scopulariopsis brevicaulis, Fusarium spp. and Scytalidium dimidiatum. Results showed a high antifungal activity of voriconazole against dermatophytes (geometric mean minimal inhibitory concentration (MIC) = 1.14 μg/mL; MIC for 50% of the organisms (MIC50) = 0.062 μg/mL; MIC for 90% of the organisms (MIC90) = 0.25 μg/mL). For S. brevicaulis, the in vitro activity of voriconazole was considerably lower (geometric mean MIC = 8.52 μg/mL; MIC50 and MIC90 = 16 μg/mL). Although voriconazole is not among the drugs recommended for the management of onychomycosis, it can be a useful alternative for recalcitrant infections.