Experimental cryptococcal myocarditis.

Rabbits and Wistar rats developed myocarditis after intramyocardial inoculation with Cryptococcus neoformans. Myocardial lesions were observed on the 1st, 2nd, 3rd, and 4th week after the inoculation in all animals. The cardiac lesion consisted of focal necrosis with accompanying lymphocytes, macrophages, and rare fibroblasts in the myocardium. Cryptococcus neoformans itself was found by PAS stain and indirect immunofluorescence stain by the 2nd week after the inoculation. Maximal cardiac lesions were observed in the 2nd week and thereafter, the lesions showed progressive scarring. In the 9th week there were fibrotic lesions, and we were not able to demonstrated cryptococcal antigens in these lesions. Fungemia and antibody for Cryptococcus neoformans were not found over the entire period. Cryptococcal meningeal lesions were observed in all animals. In the animals given an intramyocardial inoculation of saline, Pseudomonas aeruginosa, and Serratia marcescens there were no myocardial lesions. The relationship of this experimental cryptococcal myocarditis and fungal endocarditis in humans is discussed.