From Dental Procedures to Endocarditis: Cardiobacterium hominis Infection of a Bioprosthetic Mitral Valve

Prosthetic valve endocarditis (PVE) is an extremely rare but serious complication in patients with bioprosthetic heart valves following procedures such as dental work, especially when prophylactic antibiotics are not administered. We present the case of a 67-year-old male with a bioprosthetic mitral heart valve who developed subacute endocarditis caused by Cardiobacterium hominis after undergoing a dental procedure without antibiotic prophylaxis. The patient presented to the emergency department with a six-month history of worsening fatigue, weakness, intermittent fevers, and lower extremity edema. Initial evaluation with a transthoracic echocardiogram suggested infective endocarditis. A follow-up transesophageal echocardiogram confirmed bioprosthetic mitral valve endocarditis with large vegetations and paravalvular regurgitation. While admitted, blood cultures obtained from the patient's primary care physician did come back positive for C. hominis, confirming the diagnosis of C. hominis subacute endocarditis. During the patient's hospitalization, the patient developed multiple sequelae, including septic emboli to the spleen and significant anemia due to macroangiopathic hemolysis. The patient was discharged after initiation of intravenous (IV) ceftriaxone and underwent redo mitral valve replacement. He had a successful postoperative recovery and continued IV ceftriaxone for six weeks. This case highlights the diagnostic challenges of rare pathogens in PVE, particularly C. hominis, and emphasizes the importance of timely diagnosis, appropriate antibiotic therapy, and prophylactic antibiotics for high-risk patients undergoing invasive procedures.