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A 12-year-old boy with a bicuspid aortic valve is diagnosed with infective endocarditis due to methicillin-sensitive Staphylococcus aureus (MSSA). He is started on appropriate intravenous antibiotics according to culture sensitivity. After 7 days of treatment, he continues to have daily fever, and repeat blood cultures remain positive for MSSA. Repeat echocardiography shows a persistent vegetation without an increase in size and no evidence of heart failure.
What is the most appropriate next step in management?
A. Continue the same antibiotics for another 2 weeks
B. Change to oral antibiotics
C. Repeat echocardiography to look for a perivalvular abscess
D. Add corticosteroids
E. Stop antibiotics and repeat blood cultures after 48 hours
Correct answer & Explanation:
Correct Answer: C. Repeat echocardiography to look for a perivalvular abscess
Explanation
Persistent fever and positive blood cultures after 5–7 days of appropriate antibiotic therapy should raise suspicion for a local cardiac complication, particularly a perivalvular abscess, prosthetic valve infection, or another uncontrolled source of infection.
The next step is repeat echocardiography (preferably transesophageal echocardiography if feasible) to evaluate for complications that may require surgical intervention.
Why the other options are incorrect
- A. Continue the same antibiotics: Persistent bacteremia despite appropriate therapy requires investigation for uncontrolled infection rather than simply waiting.
- B. Change to oral antibiotics: Infective endocarditis requires prolonged intravenous therapy.
- D. Add corticosteroids: Corticosteroids have no routine role in infective endocarditis.
- E. Stop antibiotics: Interrupting therapy would worsen infection.
Learning Point
Persistent bacteremia beyond 5–7 days despite appropriate antibiotics is a red flag for:
- Perivalvular abscess
- Inadequate source control
- Resistant organism
- Incorrect diagnosis
Such patients require repeat imaging and early surgical assessment if complications are identified.
