Gastrointestinal and disseminated candidiasis. An experimental model in the immunosuppressed rat

An experimental model of invasive gastrointestinal (GI) candidiasis was studied in immunosuppressed rats. Normal rats were susceptible to disseminated candidiasis by intravascular inoculation (lethal dose for 50% survival [LD50], 1.6 x 10(6) blastospores). Cyclophosphamide-induced leukopenia decreased the LD50 to 1.2 x 10(4) blastospores. Feeding Candida albicans to rats resulted in low-grade GI colonization of normal rats. The intensity of colonization was increased by treatment with cyclophosphamide and broad-spectrum antibiotics. Only in animals fed Candida and treated with both antibiotics and cyclophosphamide did invasive GI lesions develop. However, hematogenous dissemination occurred in only about 10% of such rats. The addition of cortisone acetate to the treatment regimen increased the frequency of hematogenous dissemination to about 25%. Thus, disseminated candidiasis after invasive GI disease can be produced in the rat after exposure to the same predisposing factors as immunosuppressed human patients in whom the disease develops.