Acute dehiscence of a valve prosthesis 5 years after implantation

Propionibacterium acnes, a common human skin organism [Perry A.L., Lambert P.A., Under the microscope Propionibacterium acnes, Lett App Microbiol 2006; 42:185–186], mostly considered a contaminant, has rarely been associated with cases of infectious endocarditis [Vanagt W.Y., Daenen W.J., Delhaas T., Propionibacterium acnes endocarditis on an annuloplasty ring in an adolescent boy, Heart 2004; 90:56]. We report on a 48-year old man with a history of mitral valve replacement who acutely developed dyspnoea, tachypnoea and forward failure. Transesophageal echocardiography showed a dehiscence of the St. Jude mechanical mitral prosthesis necessitating urgent surgery. The prosthesis was replaced by another St. Jude mechanical valve. Blood cultures were initially negative but after a prolonged incubation period the tissue cultures became positive for Propionibacterium acnes. In cases of valvular dehiscence without macroscopic signs of endocarditis, communication between clinicians and the laboratory is important in order to incubate blood and tissue samples for a longer period of time to be able to detect exceptional causes of endocarditis.