An unusual microorganism, Aerococcus viridans, causing endocarditis and aortic valvular obstruction due to a huge vegetation.

Aerococcus viridans is not a common pathogen, and endocarditis due to A. viridans is very rare. A 44-year-old woman with persistent atrial fibrillation and rheumatic valvular heart disease was admitted with fever, sweating, weakness, and progressive shortness of breath. Transthoracic echocardiography (TTE) demonstrated a 8x9-mm vegetation attached to the right coronary cusp of the aortic valve, causing aortic obstruction. Blood cultures yielded A. viridans susceptible to penicillin. Despite optimal antibiotherapy, subsequent TTE controls revealed enlargement of the vegetation, reaching a size of 21x10 mm, and an increasing gradient across the aortic valve. The patient underwent successful aortic and mitral valve replacement and was stable in the postoperative period without any problem. This represents the first reported case of A. viridans endocarditis in which the size and location of vegetation caused obstruction to blood flow, indicating surgery.