Clinical Scenario:
A 13-year-old boy is evaluated for persistent fever and a new cardiac murmur. Echocardiography shows a vegetation on the mitral valve, but all blood cultures remain sterile. He received oral antibiotics for one week before admission.
What is the most likely reason for the negative blood cultures?
A. Fungal infection
B. Previous antibiotic therapy
C. Laboratory error
D. Viral myocarditis
E. Wrong blood culture technique
Correct answer & Explanation:
Correct Answer: B. Previous antibiotic therapy
Explanation
The most common cause of culture-negative infective endocarditis is administration of antibiotics before blood cultures are obtained.
