Mitral bioprosthetic valve endocarditis caused by an unusual microorganism, Gemella morbillorum, in an intravenous drug user.

We report a case of Gemella morbillorum mitral bioprosthetic valve endocarditis with perivalvular extension in a 44-year-old human immunodeficiency virus-positive man who is an active intravenous drug user together with review of all published cases. This is only the second reported case of Gemella morbillorum endocarditis in a patient with a prosthetic valve.