Question:medium
A lady with congenital heart disease underwent a dental extraction and developed endocarditis. Which is the organism most likely to have been involved in the pathogenesis?
A lady with congenital heart disease underwent a dental extraction and developed endocarditis. Which is the organism most likely to have been involved in the pathogenesis?
Show Hint
Mouth flora enter the blood during dental work; viridans streptococci are the classic culprit in endocarditis after dental extraction.
Updated On: Jul 8, 2026
- Staphylococcus aureus
- Streptococcus pneumoniae
- Streptococcus sanguis
- Staphylococcus epidermidis
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Note the two facts given.
The patient already has an abnormal heart (congenital heart disease) and she just had a tooth pulled. Soon after, she got endocarditis.
Step 2: Think about what a tooth extraction does to the blood.
Pulling a tooth tears the gum tissue, and the mouth is full of bacteria. For a few minutes to hours after the procedure, these bacteria leak into the bloodstream. This is a well known trigger for endocarditis in people with pre-existing valve problems.
Step 3: Match the trigger to the right bug.
The dominant bacteria of the mouth and teeth surface are the viridans streptococci, and Streptococcus sanguis is the classic named member of this group taught in relation to dental-procedure endocarditis. They are not very aggressive on their own, but they are excellent at sticking to an already damaged valve surface, which fits this patient's underlying congenital defect perfectly.
Step 4: Check why the alternatives do not fit the story.
Staph aureus goes with skin breaks, injecting drug use, or infected lines, and gives a rapidly destructive picture, which does not match a dental trigger.
Strep pneumoniae belongs to the lungs and sinuses, not the mouth flora responsible for post-dental bacteremia.
Staph epidermidis is a skin commensal mostly blamed for infections of prosthetic valves and catheters, not native valves after a tooth extraction.
Step 5: State the answer.
The dental-procedure trigger plus the pre-existing heart defect points straight to viridans streptococci from the mouth.
$\boxed{\text{Streptococcus sanguis}}$
The patient already has an abnormal heart (congenital heart disease) and she just had a tooth pulled. Soon after, she got endocarditis.
Step 2: Think about what a tooth extraction does to the blood.
Pulling a tooth tears the gum tissue, and the mouth is full of bacteria. For a few minutes to hours after the procedure, these bacteria leak into the bloodstream. This is a well known trigger for endocarditis in people with pre-existing valve problems.
Step 3: Match the trigger to the right bug.
The dominant bacteria of the mouth and teeth surface are the viridans streptococci, and Streptococcus sanguis is the classic named member of this group taught in relation to dental-procedure endocarditis. They are not very aggressive on their own, but they are excellent at sticking to an already damaged valve surface, which fits this patient's underlying congenital defect perfectly.
Step 4: Check why the alternatives do not fit the story.
Staph aureus goes with skin breaks, injecting drug use, or infected lines, and gives a rapidly destructive picture, which does not match a dental trigger.
Strep pneumoniae belongs to the lungs and sinuses, not the mouth flora responsible for post-dental bacteremia.
Staph epidermidis is a skin commensal mostly blamed for infections of prosthetic valves and catheters, not native valves after a tooth extraction.
Step 5: State the answer.
The dental-procedure trigger plus the pre-existing heart defect points straight to viridans streptococci from the mouth.
$\boxed{\text{Streptococcus sanguis}}$
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