Corynebacterium propinquum endocarditis: a confounding presentation of a rare entity.

Infective endocarditis is rarely caused by Corynebacterium species. We report a unique case of Corynebacterium propinquum endocarditis in an otherwise healthy individual, and it is the first example of this organism causing culture-negative endocarditis. Conflicting clinical and microbiological data led to the use of sequencing to confirm the causative organism. This case illustrates C. propinquum as a cause of infective endocarditis, and it demonstrates the utility of ancillary molecular diagnostic techniques to identify etiologic agents in difficult cases of infective endocarditis.