Modified Duke Criteria for Infective Endocarditis
The Modified Duke Criteria are the most widely used diagnostic criteria for infective endocarditis. They combine major criteria (positive blood cultures and echocardiographic findings) with minor criteria to categorize cases as definite, possible, or rejected.
About
The Duke criteria were originally proposed by Durack et al. in 1994 and modified in 2000 to include Q-fever as a major criterion. Major criteria include: (1) Positive blood culture for typical IE organisms (Streptococcus viridans, Streptococcus bovis, HACEK group, Staphylococcus aureus, or Enterococcus) from 2 separate cultures; (2) Persistently positive blood cultures (≥2 positive from samples drawn >12h apart, or ≥3 positive in first hour); (3) Positive echocardiogram (vegetation, abscess, new dehiscence of prosthetic valve, or new valvular regurgitation). Minor criteria include: (1) Predisposing heart condition or IV drug use, (2) Fever ≥38°C, (3) Vascular phenomena (major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, Janeway lesions), (4) Immunologic phenomena (glomerulonephritis, Osler nodes, Roth spots, positive rheumatoid factor), (5) Microbiologic evidence not meeting major criteria, (6) Echocardiographic findings not meeting major criteria.
Formula
Definite IE: 2 major, or 1 major + 3 minor, or 5 minor. Possible IE: 1 major + 1 minor. Rejected: No criteria met.
Definite IE: 2 major criteria, OR 1 major + 3 minor, OR 5 minor. Possible IE: 1 major + 1 minor, OR 3 minor. Rejected IE: alternative diagnosis, resolution with ≤4 days antibiotics, or no pathological evidence of IE at surgery/autopsy.
Score Interpretation
Infective endocarditis has a mortality of 20-30% at 1 year. Early diagnosis using the Duke criteria is critical for timely institution of appropriate antibiotic therapy and surgical intervention when indicated. The Modified Duke Criteria have a sensitivity of 80-90% for definite IE.
Rejected — 0–0
Rejected IE. Alternative diagnosis likely.
Management: Investigate alternative causes.
Possible — 1–1
Possible IE. Further evaluation needed.
Management: Serial blood cultures, repeat echo, close monitoring.
Definite — 2+
Definite IE by Modified Duke Criteria.
Management: Start empiric antibiotics, ID consult, consider surgery.
Reference Ranges
| Population | Normal Range |
|---|---|
| Patients with suspected infective endocarditis | Rejected / Possible / Definite |
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Expert infectious disease review panel.
View medical review board & editorial policy →Example Calculation
Patient with fever, Osler nodes, S. aureus bacteremia in 2 sets, and vegetation on mitral valve. Major: 2 (blood culture + echo). Minor: 2 (fever + immunologic). Definite IE (2 major).
Related Conditions
Related Medications
Common Mistakes
Counting single positive blood culture as a major criterion.
Two separate positive cultures are required for a major criterion, unless Q-fever serology is positive.
Frequently Asked Questions
What is the role of PET/CT in the Duke criteria?
References
- Li JS, et al. Proposed modifications to the Duke criteria for the diagnosis of infective endocarditis. Clin Infect Dis. 2000;30(4):633-8.