A 27-year-old man has fever, chills, malaise, and joint discomfort in his hands and knees. He looks unwell, his Temp is 39.4 C, BP 115/70 mmHg, HR 110/min, his jugular venous pressure has a prominent c-v wave. There is also a 3/6 pansystolic murmur heard at the right sternal border that increases with respiration. His lungs are clear, abdomen is soft, and joint are normal. He has multiple puncture sited on his forearms from injection drug use. Which of the following is the most likely causative organism?