Propionibacterium acnes: a rare cause of late prosthetic valve endocarditis and aortic root abscess.

Propionibacterium acnes is an anaerobic, non-spore forming, gram-positive bacillus, and is often part of the normal flora of human skin. It usually has relatively low virulence. However, it can rarely cause serious infections including infections of prosthetic valves, native valves, and annuloplasty rings. We describe a rare case of late prosthetic aortic valve endocarditis and aortic root abscess caused by P. acnes, an easily ignored pathogen.