First case of Tritirachium oryzae as agent of onychomycosis and its susceptibility to antifungal drugs.

The first case of Tritirachium oryzae isolated from an Iranian patient is reported. A 44-year-old woman with a lesion in her fingernail was examined for onychomycosis. Direct microscopic examination of the nail clippings revealed fungal filaments and inoculation of portions of the nail clippings on cultures media yielded T. oryzae after 8 days. The isolate was identified as Tritirachium spp. on the basis of gross morphological characteristics of the fungal colony and microscopic characterization of slide cultures. The diagnosis of T. oryzae was confirmed by PCR sequencing of the internal transcribed spacer domain of the rDNA gene. In vitro antifungal susceptibility test demonstrated that the fungus was susceptible to itraconazole and posaconazole. The patient was treated with oral itraconazole.