Corynebacterium diphtheriae Native Aortic Valve Endocarditis in a Patient With Prosthetic Mitral Valve: A Rare Presentation

Infective endocarditis due to non-toxigenic Corynebacterium diphtheriae is uncommon. We describe the case of a 42-year-old male with a history of mitral valve replacement with prosthetic valve for 4 years. He presented with fever, weight loss, dyspnea on exertion and orthopnea. The echocardiography demonstrated large vegetation attached on the left coronary cusp of the aortic valve with moderately severe aortic regurgitation but sparing of the prosthetic mitral valve. Three separate blood cultures grew Corynebacterium species. The patient underwent aortic valve replacement due to valvular dysfunction and congestive heart failure. C. diphtheriae DNA was detected by 16 S rDNA polymerase chain reaction (PCR) from the heart valve tissue. The patient recovered completely with combine antibiotics and surgical intervention. He was discharged from the hospital with good clinical outcome.