Phialophora mutabilis endocarditis.

This is the first reported case of fungal endocarditis due to vegetative growth of Phialophora mutabilis on a prosthetic mitral valve. The patient had rheumatic heart disease with mitral and aortic stenosis. Four months after the mitral and aortic valves had been replaced by prostheses the patient developed congestive failure. Because of increased left atrial pressure, the mitral prosthesis was replaced. A large matted obstructive fungal vegetation was found on the prosthesis. Culture of this vegetation grew Phialophora mutabilis. The patient died postoperatively, and at autopsy the fungus was not found in other tissues. Culturally and morphologically, P. mutabilis shows wide variation in pigmentation, colonial and microscopic appearance. Conidia formation from intercalary cells along the hyphae is somewhat similar to that of Aureobasidium spp. P. mutabilis was injected into mice. Mice pretreated with cortisone died 3 to 5 weeks after intraperitoneal inoculation, while the majority of untreated mice died within 20 weeks of inoculation.