ABSTRACT
Infectious endocarditis (IE) is an inflammatory disease of cardiac valves and endocardium of different origin. Subacute IE is a specific form of sepsis associated with the presence of the site of infection in the heart responsible for recurrent septicemia, embolism, and progressive changes in the immune system leading to nephritis, vasculitis, synovitis, and polyserositis. This form develops in response to a low-virulent pathogen (e.g.fungi) or as a result of inefficient antibacterial therapy. A patient is described presenting with fibrous body, aortic and mitral valve infection by the alga Prototheca wickerhamii associated with primary (myeloperoxidase) immunodeficiency. Recent data on diagnostics and treatment of subacute IE are presented.