A 72-year-old male who is known to have aortic stenosis
presents with a history of feeling generally unwell and a low-grade fever. He
also gives a history of a change in bowel habit. On examination he is noted to
have splinter haemorrhages, early clubbing and there is an early diastolic
murmur at the left sternal edge, which has not been noted earlier.
In this patient blood cultures are taken and a significant
growth is noted.
Which of the following organisms is likely to be isolated?