What are the components of Duke's criteria for diagnosing Infective Endocarditis (IE)?

Components of Duke's Criteria for Diagnosing Infective Endocarditis (IE)

The Modified Duke Criteria classify cases of infective endocarditis as "definite," "possible," or "rejected" based on specific major and minor criteria, which are essential for accurate diagnosis and timely treatment to reduce mortality and morbidity. 1

Diagnostic Categories

• Definite IE: Requires either:

  • Pathological criteria: Microorganisms or pathological lesions confirmed by histology
  • Clinical criteria: 2 major criteria, or 1 major criterion and 3 minor criteria, or 5 minor criteria 2, 1

• Possible IE: Requires either:

  • 1 major criterion and 1 minor criterion, or
  • 3 minor criteria 2

• Rejected IE: When there is:

  • Firm alternative diagnosis explaining evidence of IE, or
  • Resolution of IE syndrome with ≤4 days of antibiotic therapy, or
  • No pathological evidence of IE at surgery/autopsy after ≤4 days of antibiotics, or
  • Does not meet criteria for possible IE 2

Major Criteria

1. Blood Culture Positive for IE

• Typical microorganisms from 2 separate blood cultures:

  • Viridans streptococci
  • Streptococcus bovis/gallolyticus
  • HACEK group
  • Staphylococcus aureus (both community and hospital-acquired)
  • Community-acquired enterococci without primary focus 2, 1

• Persistently positive blood cultures:

  • At least 2 positive cultures drawn >12 hours apart, or
  • All 3 or majority of ≥4 separate blood cultures (first and last drawn ≥1 hour apart) 2, 1

• Single positive blood culture for Coxiella burnetii or anti-phase 1 IgG antibody titer >1:800 2, 1

2. Evidence of Endocardial Involvement

• Echocardiogram positive for IE:

  • Oscillating intracardiac mass on valve/supporting structures
  • Abscess
  • New partial dehiscence of prosthetic valve
  • New valvular regurgitation 2, 1

• Advanced imaging findings (in modified criteria):

  • Cardiac CT showing paravalvular lesions
  • 18F-FDG PET/CT or radiolabeled leukocyte SPECT/CT findings around prosthetic valves 1

Minor Criteria

1. Predisposition: Predisposing heart condition or injection drug use 2, 1

2. Fever: Temperature >38°C (100.4°F) 2, 1

3. Vascular phenomena:

   • Major arterial emboli
   • Septic pulmonary infarcts
   • Mycotic aneurysm
   • Intracranial hemorrhage
   • Conjunctival hemorrhages
   • Janeway lesions 2, 1

4. Immunologic phenomena:

   • Glomerulonephritis
   • Osler's nodes
   • Roth spots
   • Rheumatoid factor 2, 1

5. Microbiological evidence:

   • Positive blood culture not meeting major criteria
   • Serological evidence of active infection with organism consistent with IE 2, 1

Important Clinical Considerations

• Transesophageal echocardiography (TEE) has higher sensitivity than transthoracic echocardiography (TTE) and is recommended for:

  • Patients with prosthetic valves
  • Suspected complicated IE
  • Poor quality TTE images 1

• The diagnostic accuracy of the Modified Duke Criteria is highest when applied at the end of patient evaluation rather than at initial presentation 1

• Prior antibiotic therapy can lead to blood culture-negative IE, which may result in misclassification of cases 3, 4

• In a study of pathologically proven IE cases, 24% remained misclassified as "possible IE" despite using Duke criteria, especially in culture-negative and Q-fever IE 4

• The modification to include S. aureus bacteremia as a major criterion regardless of source (nosocomial or community-acquired) improved diagnostic accuracy 2, 5

• The elevation of Q-fever serology from minor to major criterion has enhanced detection of this specific form of endocarditis 6, 5