First case report of onychomycosis caused by Exophiala alcalophila.

A 46-year-old woman from Colombia, without any medical comorbidities, presented with marked yellowish discoloration of both big toenails, suggestive of onychomycosis, and malalignment of the nail plate. Culture of nail scrapings grew dark-pigmented, mucoid, yeast-like colonies identified as Exophiala alcalophila by ITS sequencing. Broth microdilution identified the isolate as resistant to fluconazole and the echinocandins. The patient refused antifungal treatment. This case highlights the importance of black yeast-like fungi as etiological agents of onychomycosis.