Gemella morbillorum prosthetic valve endocarditis.

The authors describe a case of prosthetic valve infective endocarditis (IE) caused by Gemella morbillorum (GM), a gram-positive coccus that grows slowly in culture and occasionally causes a subacute to chronic form of IE. To the author's knowledge, this is the third case of GM prosthetic valve IE to be reported. Subacute to chronic IE caused by slow-growing organisms can be subtle in presentation and should be suspected in patients who have prosthetic valves presenting with worsening heart failure.