Duke Criteria for Infective Endocarditis
Diagnostic Calculator for Healthcare Professionals
The Duke Criteria are clinical guidelines used to diagnose infective endocarditis (IE), a serious infection of the heart’s inner lining and valves. First proposed in 1994 and subsequently modified, these criteria incorporate clinical, microbiological, and echocardiographic findings to classify cases as definite, possible, or rejected infective endocarditis.
Duke Criteria Components
Major Criteria
- Positive Blood Cultures:
- Typical microorganisms for IE from two separate blood cultures
- Persistently positive blood cultures
- Evidence of Endocardial Involvement:
- Positive echocardiogram (oscillating intracardiac mass, abscess, new partial dehiscence of prosthetic valve)
- New valvular regurgitation
Minor Criteria
- Predisposing heart condition or intravenous drug use
- Fever >38°C (100.4°F)
- Vascular phenomena
- Immunological phenomena
- Microbiological evidence (positive blood culture not meeting major criterion)
- Echocardiographic findings consistent with IE but not meeting major criterion
Diagnostic Classification:
- Definite IE: 2 major criteria OR 1 major + 3 minor criteria OR 5 minor criteria
- Possible IE: 1 major + 1 minor criterion OR 3 minor criteria
- Rejected: Firm alternative diagnosis OR resolution of IE syndrome with ≤4 days antibiotics
Duke Criteria Calculator
Duke Criteria Assessment
The Duke criteria are a standardized set of major and minor clinical criteria used to diagnose infective endocarditis (IE) and to classify the likelihood as definite, possible, or rejected. They were first published in 1994 and modified in 2000 (“modified Duke criteria”), and they remain widely used in clinical practice and research, although further updates (e.g. 2023 Duke-ISCVID criteria) now exist.
Their purpose is to bring structure and reproducibility to the diagnosis of a disease that often presents with non-specific symptoms and diverse manifestations.
Core structure of the (modified) Duke criteria
Major criteria (simplified)
- Positive blood cultures typical for IE
- Typical organisms (e.g. viridans streptococci, Streptococcus bovis, HACEK group, Staphylococcus aureus, community-acquired enterococci) from two separate blood cultures, or
- Persistently positive blood cultures meeting defined timing requirements, or
- Coxiella burnetii (single positive culture or high phase-I IgG titre in earlier definitions).
- Evidence of endocardial involvement on imaging (usually echocardiography)
- Vegetation, abscess, new partial dehiscence of prosthetic valve, or
- New valvular regurgitation (change in murmur alone is insufficient).
Minor criteria (simplified)
- Predisposing factor – pre-existing heart disease or IV drug use
- Fever ≥ 38°C
- Vascular phenomena – e.g. major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, Janeway lesions
- Immunologic phenomena – e.g. glomerulonephritis, Osler’s nodes, Roth spots, rheumatoid factor
- Microbiological evidence not meeting a major criterion – e.g. positive blood cultures that don’t fulfil the “major” definition or appropriate serology
How the Duke criteria classify infective endocarditis
Using the clinical modified Duke criteria, IE is classified as:
- Definite infective endocarditis (clinical), if any of:
- 2 major criteria, or
- 1 major + 3 minor criteria, or
- 5 minor criteria
- Possible infective endocarditis, if any of:
- 1 major + 1 minor criterion, or
- 3 minor criteria
- Rejected infective endocarditis, if:
- A firm alternative diagnosis explains the findings, or
- Clinical manifestations resolve with ≤4 days of antibiotics, or
- No evidence of IE at surgery/autopsy after ≤4 days of antibiotics, or
- The combination of findings does not meet even the “possible” criteria.
⚠️ Important
- Duke criteria are an aid for experienced clinicians, not a stand-alone diagnostic test.
- Echocardiography quality, blood culture technique, and local epidemiology all strongly influence interpretation.
- The HTML tool below is a teaching/decision aid, not a substitute for specialist consultation, guidelines, or clinical judgment.
