Corynebacterium Bacteremia in a High-risk Host: A Diagnostic Dilemma of Contamination Versus True Infective Endocarditis.

Corynebacterium species are often regarded as skin contaminants when isolated from clinical cultures. However, in select high-risk patients, these organisms can lead to significant infections, including infective endocarditis. We present the case of a 76-year-old woman with multiple comorbidities, including end stage renal disease (ESRD) on hemodialysis and an exposed tunneled central catheter, who developed Corynebacterium-associated native mitral valve endocarditis requiring surgical intervention. Despite prompt antimicrobial therapy and bioprosthetic valve replacement, her hospital course was complicated by heart block, empyema, and eventual cardiac arrest. This case highlights the importance of recognizing Corynebacterium as a potential pathogen in vulnerable patients and reviewing the growing body of literature on this rare but serious cause of endocarditis.