What makes a blood culture result a "major" criterion?

A major criterion requires either typical IE organisms (Streptococcus viridans, Streptococcus bovis, HACEK group, Staphylococcus aureus, or community-acquired Enterococcus) in two separate cultures, OR persistently positive blood cultures drawn >12 hours apart (≥2 of 3, or a majority of ≥4 cultures with the first and last drawn ≥1 hour apart), OR a single positive culture for Coxiella burnetii or anti-phase 1 IgG antibody titer >1:800.

What echocardiographic findings satisfy the major criterion?

Oscillating intracardiac mass on a valve or supporting structure, in the path of regurgitant jets, or on implanted material; an abscess; or new partial dehiscence of a prosthetic valve. New valvular regurgitation alone does not satisfy the criterion. Positive 18F-FDG PET/CT or radiolabeled leukocyte SPECT/CT (for prosthetic valves implanted >3 months) also counts.

Can the classification change during admission?

Yes. Duke classification should be reassessed as new culture results, echo findings, or clinical data become available. A Possible case may upgrade to Definite, or downgrade to Rejected if a firm alternative diagnosis emerges or symptoms resolve rapidly with short antibiotic courses.

Does this tool store patient information?

No. All calculations run entirely in your browser. No data is transmitted to any server.

Are the Duke criteria sufficient to rule out endocarditis?

Not on their own. The Rejected classification requires a firm alternative diagnosis or rapid resolution with ≤4 days of antibiotics — not merely absence of criteria. Clinical suspicion, repeat cultures, and specialist input are essential when IE is considered.

Duke Endocarditis Criteria

Name: Duke Endocarditis Criteria
Availability: InStock
Author: Nham Vu

Select major and minor Duke criteria to classify infective endocarditis as Definite, Possible, or Rejected.

Duke Criteria

Major Criteria

Major 1 — Positive Blood Cultures

Typical organisms in ≥2 cultures, persistently positive cultures, or single positive for Coxiella burnetii / anti-phase 1 IgG >1:800

Present

Major 2 — Evidence of Endocardial Involvement

Echo: oscillating mass, abscess, or new prosthetic valve dehiscence; new valvular regurgitation; or positive 18F-FDG PET/CT (prosthetic valve >3 months)

Present

Minor Criteria

Minor 1 — Predisposing Condition

Predisposing heart condition (valvular disease, congenital HD, prior IE, prosthetic valve) or intravenous drug use

Present

Minor 2 — Fever

Temperature ≥38.0 °C (100.4 °F)

Present

Minor 3 — Vascular Phenomena

Major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhage, or Janeway lesions

Present

Minor 4 — Immunologic Phenomena

Glomerulonephritis, Osler nodes, Roth spots, or positive rheumatoid factor

Present

Minor 5 — Microbiologic Evidence

Positive blood culture not meeting a major criterion, or serologic evidence of active infection with organism consistent with IE

Present

Classification Result

Major criteria

Minor criteria

Rejected / Unclassified

Classification Rules

Definite: 2 major; or 1 major + 3 minor; or 5 minor
Possible: 1 major + 1 minor; or 3 minor
Rejected: firm alternative diagnosis, resolution ≤4 days antibiotics, or criteria not met

Summary

Select major and minor Duke criteria to classify infective endocarditis as Definite, Possible, or Rejected.

How it works

Review the two major criteria: positive blood cultures (qualifying organisms or persistent bacteremia) and evidence of endocardial involvement on echocardiography or positive 18F-FDG PET.
Review the five minor criteria: predisposing cardiac condition or IV drug use; fever ≥38 °C; vascular phenomena (emboli, Janeway lesions, mycotic aneurysm); immunologic phenomena (Osler nodes, Roth spots, RF, GN); and microbiologic evidence not meeting a major criterion.
Check each criterion that is present in the patient.
The tool tallies major and minor counts in real time and applies the Duke classification rules to return Definite, Possible, or Rejected.
Use the result alongside clinical judgment — Duke criteria are a diagnostic aid, not a substitute for specialist evaluation.

Use cases

Rapid bedside classification of suspected endocarditis cases.
Teaching house officers the major and minor Duke criteria.
Documenting clinical reasoning for suspected IE in progress notes.
Deciding on empirical antibiotic therapy urgency before culture results.
Determining need for urgent echocardiography in high-risk presentations.
Reviewing criterion weighting for educational or audit purposes.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu