Experimental fusarial hyalohyphomycosis in a murine model

The pathogenicity of two clinical strains of Fusarium solani was studied in normal and transiently neutropenic outbred CF₁ and CD₁ male mice. Three inocula (5 × 10⁵, 1 × 10⁶, and 5 × 10⁶ spores/animal) were tested. Groups of 10 mice each were injected with a single intravenous dose of one inoculum. Mortality correlated with the dose of inoculum, as survival was significantly shorter in mice injected with 5 × 10⁶ cfu/mouse than in mice that received 1 × 10⁶ or 5 × 10⁵ cfu/mouse (P < .001). Necrotizing abscesses with acute branching septate hyphae, neutrophil and macrophage infiltration, and hemorrhage were observed. The median survival of neutropenic mice was shorter than that of normal mice (P < .001). Neutropenic mice did not show evidence of an inflammatory cellular reaction and exhibited significantly higher numbers of fungi per gram of infected tissue (P < .001). Intact host defenses in normal mice were able to confine the infection to the kidneys after initial dissemination. In contrast, disseminated infection persisted in most organs in immunosuppressed animals.