Fusarium Causing Necrotizing Myositis and Tibial Periosteitis in an Immunocompetent Patient

<i>Fusarium</i> species are filamentous fungi that are ubiquitous in the environment, residing mainly in soil and associated with plants. While primarily plant pathogens, there are over 1000 subspecies (ssp) of <i>Fusarium</i>, and the more pathogenic ssp have been responsible for billions of dollars in economic losses associated with maize, rice, and wheat crops. <i>Fusarium</i> ssp have been linked to human pathogenicity, with invasive fungal infections occurring mainly in patients with hematologic malignancies, specifically leukemia. Infections with <i>Fusarium</i> spp are uncommon in immunocompetent patients, but invasive infections such as osteomyelitis are even rarer. We present a case of necrotizing myositis and tibial periosteitis in an otherwise healthy patient in the fourth decade of life. After initial diagnostic challenges and worsening condition on broad-spectrum antimicrobials tailored to bacterial pathogens, <i>Fusarium</i> was diagnosed by intraoperative cultures and histopathology. As such, antifungal coverage with amphotericin B and voriconazole was added, resulting in substantial improvement of the infection. The patient was eventually transitioned to oral voriconazole with an anticipated six to eight week course and close follow-up. At the time of preparing this report, the patient has been followed in the outpatient setting and continues to show significant improvement.