# Fusarium Causing Necrotizing Myositis and Tibial Periosteitis in an Immunocompetent Patient

## TL;DR

A healthy adult developed a rare Fusarium fungal infection causing muscle and bone inflammation, which was successfully treated with antifungal drugs.

## Contribution

This case report highlights the rare occurrence of Fusarium infection in an immunocompetent individual and its successful treatment.

## Key findings

- Fusarium infection was diagnosed in an otherwise healthy patient with necrotizing myositis and tibial periosteitis.
- Antifungal treatment with amphotericin B and voriconazole led to significant clinical improvement.
- The patient transitioned to oral voriconazole and showed continued recovery during outpatient follow-up.

## Abstract

Fusarium 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 Fusarium, and the more pathogenic ssp have been responsible for billions of dollars in economic losses associated with maize, rice, and wheat crops. Fusarium ssp have been linked to human pathogenicity, with invasive fungal infections occurring mainly in patients with hematologic malignancies, specifically leukemia. Infections with Fusarium 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, Fusarium 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.