In the Duke criteria for infective endocarditis, which finding satisfies a major criterion?

• A. Vegetation on echocardiography
• B. Fever and bacteremia
• C. Chest radiograph abnormality
• D. Positive rheumatoid factor

Answer: (A)

The key idea is that major criteria in the Duke criteria are direct evidence of endocardial involvement. A vegetation seen on echocardiography is exactly that: it is a visible, oscillating mass attached to a valve or other endocardial surface, showing the heart structures are infected. This direct imaging finding satisfies a major criterion and supports a diagnosis of infective endocarditis.

Fever by itself is nonspecific and falls under minor criteria; bacteremia becomes major only if the blood cultures grow a typical organism known to cause IE, not just any bacteremia. Chest radiograph abnormalities are not part of the Duke major criteria, and positive rheumatoid factor is an immunologic minor criterion.