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 x 10(5), 1 x 10(6), and 5 x 10(6) 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 x 10(6) cfu/mouse than in mice that received 1 x 10(6) or 5 x 10(5) cfu/mouse (P less than .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 less than .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 less than .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.