2025 Volume 74 Issue 3 Pages 628-633
Candida allociferrii is a rare yeast-like fungus that has been proposed to be one of the species within the Stephanoascus ciferrii complex. In Japan, only one case of isolation from an orbital abscess has been previously reported. We herein report a case of otomycosis caused by C. allociferrii. The patient was a male in his 50s who presented with pruritus and otorrhea in the right ear. A sample of ear discharge was submitted for examination. On the first day of culture, small colonies were observed on the medium, thus prompting Gram staining and extended incubation. In the Gram staining of the colonies, yeast-like fungi with spores arranged in parallel on one side of the hyphae were observed. By the fifth day of culture, the colonies exhibited wrinkles and appeared to be embedded in the medium. Such Gram staining and colony morphology suggested the possibility that this fungus represented a major Candida species. However, biochemical characterization and mass spectrometry failed to provide an accurate species identification. Sequencing of the ITS and D1/D2 regions finally identified the isolate as C. allociferrii. These findings indicate that genetic sequencing is useful for the precise identification of this species, and previous reports have suggested that C. allociferrii exhibits resistance to azole antifungals. In the present case, the MIC of fluconazole was elevated. Given that fluconazole is often the first-line treatment for invasive candidiasis, early morphological and culture-based presumptive identification followed by rapid reporting may help to allow medical personnel to perform timely and appropriate treatment.
