A 66-year-old man develops fever 10 days after mechanical aortic valve replacement. Blood cultures grow methicillin-resistant Staphylococcus epidermidis. Transoesophageal echo shows a vegetation at the annulus. Which feature best identifies this as EARLY prosthetic valve endocarditis?
- A Vegetation confined to the leaflet surface with normal white cell count
- B Onset beyond 6 months with viridans streptococcal bacteraemia from dental work
- C Onset within 60 days of surgery with coagulase-negative staphylococcal aetiology ✓
- D Positive rheumatoid factor and elevated erythrocyte sedimentation rate
Correct answer: C. Onset within 60 days of surgery with coagulase-negative staphylococcal aetiology
Explanation
Early prosthetic valve endocarditis is defined as onset within 60 days of surgery and is most often caused by coagulase-negative staphylococci such as S. epidermidis acquired perioperatively, frequently involving the annulus with abscess formation. Late PVE occurs beyond 60 days and mirrors community-acquired native valve disease with viridans streptococci and enterococci. Elevated ESR and positive rheumatoid factor are minor Duke criteria, not discriminators of timing.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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