Abstract

Background and Aim: Rhodotorula mucilaginosa (R. mucilaginosa) has emerged as a potential pathogen in immunosuppressed hosts. This fungal agent rarely causes onychomycosis in immunocompetent hosts. In this study, onychomycosis caused by this strain on different fingernails and toenails in an Immunocompetent young adult is reported. Case Report: The patient was an 18-year-old woman with clinical symptoms of powdery, hyperkeratosis brief around erythema in the distal part of a toenail and deformity with a groove on surface of a fingernail who was referred to the Medical Mycology Laboratory of Hazrat Ghaem therapeutic center. After diagnostic procedures, he was treated with oral itraconazole 200 mg/day for 2 months along with topical clotrimazole and sulfacetamide ointment and was cured. The nails responded satisfactorily to the treatment. After two months of stopping the drug, the absence of fungus elements in the clinical samples was confirmed. Diagnosis and identification of the fungus was confirmed by morphological characteristics, culture, and DNA molecular method, and R. mucilaginosa was reported as the etiological agent of onychomycosis. Antifungal drug susceptibility was determined in laboratory using the disk diffusion method according to CLSI guidelines. Conclusion: The isolated species was reported as an unusual species of onychomycosis, which needs to be considered by mycology laboratory and clinical specialists for its sensitivity to ketoconazole, itraconazole, and econazole and its resistance to amphotericin B and nystatin. © 2023 Baqiyatallah University of Medical Sciences. All rights reserved.