Abstract
A case of acute infective endocarditis caused by diphtheroids in a healthy young male is described. The pathogenic role of the diphtheroids was verified by recognition of the same bacterium in 6 consecutive blood cultures and simultaneous rise of specific antibody titers. The infection was effectively controlled by antibiotic treatment, but destruction of the aortic valve led to progressive heart failure irresponsive to medical treatment. The affected valve was successfully replaced by a prosthetic valve, and the patient made a complete recovery. Neither congenital or acquired cardiac defects, nor signs of immunological deficiency could be detected.