QuestionSBA
QuestionChoice
This is the most common cause of infective endocarditis, but not in this patient. His recent dental surgery makes streptococcus mutans a more likely diagnosis.
10007796
b
Staphylococccus aureus
QuestionChoice
As the stem mentioned, the patient is diagnosed with infective endocarditis. In most cases the most common causative pathogen would be staphylococcus aureus. However the patient mentions that he has had recent dental surgery. In dental surgery, there is likely to be bleeding within the gums/oral cavity. Streptococcus mutans is a gram-positive bacterium that is a commensal in the oral cavity and hence it is possible for some of the bacteria from the oral cavity to be transferred into the bloodstream. These bacteria can lodge onto a vegetation within the heart and cause further fibrin deposition and platelet aggregation. They can also form microcolonies, in which the superficial colonies embolise to further tissues such as the skin of the hands, leading to e.g. Osler nodes.
10007795
a
Streptococcus mutans
QuestionChoice
No, this is not a common cause of infective endocarditis.
10007798
d
Streptococcus pyogenes
QuestionChoice
No, this is a coagulase negative staphylococci which would be present in prosthetic valve replacement <1 year post-operation.
10007797
c
Staphylococcus epidermidis
QuestionChoice
No, this is not a common cause of infective endocarditis.
10007799
e
Escherichia coli
Concept
Chapter
2693
3710
Infective Endocarditis
Topic
134
Cardiology
14106
A 45-year-old man presents to the GP with fatigue and recent weight loss. He reports having suffered some episodes of sweating during the night and also a loss of appetite.

On examination of his hands, he appears to have symptoms related to septic thrombi, such as Osler nodes and splinter haemorrhages. He also mentions having some upper teeth pain due to his recent dental surgery. Prior to this episode, he was fit and well, with no significant past medical history.

A diagnosis of infective endocarditis is made.

Which of the following is the most likely causative pathogen?
a