MS-2668

A 27-year-old man is brought to the emergency department after being found unconscious at home. He is a known intravenous drug user.

Upon examination, he has a fever of 38.5oC and a new murmur is heard loudest in the tricuspid region. An echocardiogram reveals a vegetation on the tricuspid valve.

A blood culture is taken to identify the organism causing the infection. What is the most likely organism growing on the valve?