Polymicrobial native valve endocarditis due to Bacillus cereus and Cardiobacterium hominis

Abstract

We present a case of polymicrobial subacute bacterial endocarditis and bacteremia with Bacillus cereus and Cardiobacterium hominis in a 72-year-old man with pre-existing mitral valve disease and prior mitral valve repair who presented with renal failure and glomerulonephritis. Bacillus is often a contaminant in blood cultures but has been rarely implicated in patients with invasive infections such as endocarditis. Intravenous drug use, prosthetic heart valves, valvular heart disease and venous catheters are the most frequently described risk factors for Bacillus bacteremia and endocarditis in the medical literature. Management is challenging as Bacillus is resistant to penicillin and cephalosporin antibiotics due to production of beta-lactamase. Polymicrobial endocarditis is uncommon and when it occurs typically involves Staphylococcal species. To our knowledge, this is the first reported case of polymicrobial endocarditis in which both Bacillus and a HACEK organism are implicated.