Failing to treat subacute bacterial endocarditis or treating it insufficiently, e.g., with an inadequate antibiotic regimen, will lead to destruction of the valvular leaflets of the heart, in this case, the aortic and the mitral valves. This leaflet destruction is characterized by vegetations on the valve leaflets and regurgitation (leakiness) of the infected valve that is detectable on echocardiography. Timely treatment of subacute bacterial endocarditis is effective in preventing detectable vegetations by echocardiography and will lead to preservation of valve integrity and function.
Subacute bacterial endocarditis follows an indolent course stretching over a period of weeks to months. Most commonly, the organism involved is Streptococcus viridans. Streptococcus viridans causes 30-40% of all cases of endocarditis. In contrast, acute bacterial endocarditis follows a rapid and malignant course, measured in days to weeks. Typically, the organism involved is more virulent, such as Staphylococcus aureus.