Corynebacterium jeikeium native valve infective endocarditis case report: a confirmed microbiological and pathological diagnosis from heart valvular tissue

BACKGROUND: The Modified Duke criteria is an important structured schematic for the diagnosis of infective endocarditis (IE). Corynebacterium jeikeium is a rare cause of IE that is often resistant to standard IE anti-microbials. We present a case of C. jeikeium IE, fulfilling the Modified Duke pathological criteria. CASE SUMMARY: A 50-year-old male presented with left leg peripheral vascular disease with septic changes requiring amputation. Routine echocardiography post-amputation demonstrated severe aortic valve regurgitation with vegetations that required valve replacement. Two initial blood cultures from a single venepuncture showed Streptococcus mitis which was treated with penicillin G prior to surgery. Subsequent aortic valve tissue cultured C. jeikeium with suggestive IE histological valvular changes and was successfully treated on a prolonged course of vancomycin. DISCUSSION: This is the first C. jeikeium IE case diagnosed on heart valvular tissue culture and highlights the importance for the fulfilment of the Modified Duke criteria in diagnosing left-sided IE. Mixed infection IE is rare, and this case possibly represents an unmasking of resistant C. jeikeium IE following initial treatment of penicillin G.