Question

Infective endocarditis after tooth extraction is probably due to?

• A. Streptococcus viridans
• B. Streptococcus pneumoniae
• C. Streptococcus pyogenes
• D. Staphylococcus aureus

Hint:

Which mouth commensal seeds damaged valves after dental work?

Answer 1

The Correct Option is A

Step 1: Infective endocarditis following dental procedures is linked to the normal flora of the mouth that enters the bloodstream during the procedure.

Step 2: Viridans streptococci are normal residents of the mouth and upper respiratory tract. They cause a transient bacteremia after tooth extraction or other dental work, then settle on damaged, prosthetic or congenitally diseased heart valves and grow into vegetations.

Step 3: In patients with pre-existing cardiac lesions, viridans streptococci (with Streptococcus sanguis often responsible) are the classic cause of subacute bacterial endocarditis. Their adherence to biological surfaces explains this predilection.

Step 4: The distractors fit other diseases. Strep. pneumoniae causes pneumonia and meningitis, Strep. pyogenes causes pharyngitis and rheumatic fever, and Staph. aureus typically causes acute endocarditis (often in IV drug users), not the post-dental subacute form. Hence option (a) Streptococcus viridans is correct.