24th June 2026

A 72-year-old female presents generally unwell with a fever, malaise, and shortness of breath.

A 72-year-old female presents generally unwell with a fever, malaise, and shortness of breath. Examination and subsequent investigations confirm a diagnosis of infective endocarditis, and she is commenced on antimicrobial therapy. She has no previous cardiac history, has no indwelling prosthetic material, and until admission was fit and well, volunteering in the local library. On further questioning, she mentions that she has had some trouble with her teeth, but is afraid of going to the dentist and hasn’t been to see anyone. On further examination, she is found to have a large dental abscess and several decaying teeth. 

What is the most likely causative organism of her infective endocarditis? 

Select the SINGLE most appropriate option from the list below. Select ONE option only.