High azole MICs in Fusarium spp.: a key factor in treatment decisions for cancer patients?

Invasive fusariosis (IF) is an exceptionally severe disease, particularly affecting patients with prolonged neutropenia. Even with antifungal therapy, mortality rates remain high, emphasizing the need for stringent control over hospital environment and further research to enhance patient outcomes. This study aims to assess the antifungal susceptibility of clinical and environmental Fusarium isolates and their clinical relevance in a cancer hospital. Sixteen environmental and 21 clinical isolates were identified, with the Fusarium solani species complex being the most common. Amphotericin B demonstrated in vitro activity, but most isolates exhibited elevated minimum inhibitory concentrations (MICs) for azoles. A total of 80% of patients had IF, primarily those with hematological malignancies, and the 30-day mortality rate was 43.8%. Isolates with elevated MICs were often managed with combination therapy. In conclusion, elevated azole MICs may lead to increased use of combination therapy in real-world clinical settings. Our findings emphasize the importance of careful interpretation of antifungal susceptibility testing results in IF management.