A 28-year-old male who is
known to be an intravenous drug abuser is admitted with a history of fever
with chills and rigors. On examination he is febrile, has multiple puncture
marks and thrombosed veins in his skin. He has a pulse rate of 120 beats per
minute, his jugular venous pressure is elevated with a predominant systolic
wave and there is a pan systolic murmur at the left sternal edge, which
increases with inspiration. The liver is enlarged and pulsatile. You arrange
for blood cultures in this patient.
Which of the following
organisms is the most likely to be isolated in this patient?