Fungal Osteomyelitis of a Diabetic Foot Infection Caused by Trichosporon asahii: A Case Report

ABSTRACT Diabetic foot bacterial osteomyelitis is a serious infection that can lead to major amputations. However, fungal osteomyelitis in a diabetic foot ulcer is uncommon and has been underrecognized. It typically occurs in patients with underlying immunocompromised status and is associated with poor outcomes. Fungal osteomyelitis might be overlooked or diagnosed late because of underrecognition and the inability to differentiate it from bacterial osteomyelitis without specific laboratory testing, such as fungal culture of bone and histopathology including fungal stain. Treating fungal osteomyelitis involves a long course of antifungal treatment, along with surgical management and intensive wound care. In this report, the authors describe the case of a 78-year-old woman with peripheral arterial disease and diabetes who developed dry gangrene complicated by osteomyelitis due to the fungus Trichosporon asahii in the distal phalange of her right hallux. Initially, her pain and erythema around the gangrene improved with voriconazole; however, her gangrene worsened, likely because of nonadherence to wound care and offloading, and her comorbidities. Ultimately, she underwent a right foot guillotine transmetatarsal amputation. The authors also review the literature on fungal osteomyelitis, particularly in the context of diabetic foot infections and Trichosporon asahii infections.