What are the Dukes (Duke) criteria for diagnosing infective endocarditis in patients with pre-existing heart conditions, such as those with prosthetic heart valves or a history of heart valve problems?

Duke Criteria for Diagnosing Infective Endocarditis

The modified Duke criteria remain the gold standard for diagnosing infective endocarditis, requiring either 2 major criteria, 1 major plus 3 minor criteria, or 5 minor criteria for definite diagnosis, with enhanced imaging modalities (cardiac CT, PET/CT) now incorporated as major criteria particularly for prosthetic valve cases. 1

Definite Infective Endocarditis

A diagnosis of definite IE requires meeting one of the following combinations: 1

Pathological Criteria

• Microorganisms demonstrated by culture or histological examination of vegetation, embolized vegetation, or intracardiac abscess specimen 1
• Pathological lesions showing active endocarditis (vegetation or intracardiac abscess) confirmed by histology 1

Clinical Criteria (any one of):

• 2 major criteria 1
• 1 major criterion AND 3 minor criteria 1
• 5 minor criteria 1

Major Criteria

Blood Culture Positive for IE

Typical microorganisms from 2 separate blood cultures: 1

• Viridans streptococci, Streptococcus gallolyticus (S. bovis), HACEK group, Staphylococcus aureus 1
• Community-acquired enterococci in the absence of a primary focus 1

Persistently positive blood cultures: 1

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

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

Important modification: Any S. aureus bacteremia should be considered a major criterion regardless of whether nosocomially acquired or if a removable source is present 2

Imaging Positive for IE

Echocardiographic findings: 1

• Oscillating intracardiac mass (vegetation) on valve or supporting structures, in path of regurgitant jets, or on implanted material 1
• Abscess, pseudoaneurysm, intracardiac valvular perforation or aneurysm 1
• New partial dehiscence of prosthetic valve 1
• New valvular regurgitation (worsening or changing of pre-existing murmur is NOT sufficient) 1

Advanced imaging (2015 ESC additions - critical for prosthetic valves): 1

• Paravalvular lesions identified by cardiac CT 1
• Abnormal activity around prosthetic valve site on ¹⁸F-FDG PET/CT (only if prosthesis implanted >3 months) or radiolabeled leukocyte SPECT/CT 1

Echocardiography approach: TEE is recommended for patients with prosthetic valves, rated at least "possible IE" by clinical criteria, or complicated IE (paravalvular abscess); TTE should be the first test in other patients 1

Minor Criteria

1. Predisposition: Predisposing heart condition (prosthetic valve, prior IE, mitral valve prolapse, bicuspid aortic valve, valve stenosis/insufficiency) or injection drug use 1, 3

2. Fever: Temperature >38°C 1

3. Vascular phenomena: Major arterial emboli, septic pulmonary infarcts, infectious (mycotic) aneurysm, intracranial hemorrhage, conjunctival hemorrhages, Janeway lesions 1

   • 2015 ESC addition: Identification of recent embolic events or infectious aneurysms by imaging only (silent events) now counts as minor criterion 1

4. Immunologic phenomena: Glomerulonephritis, Osler's nodes, Roth's spots, rheumatoid factor 1

5. Microbiological evidence: Positive blood culture that does not meet major criterion (excludes single positive cultures for coagulase-negative staphylococci and organisms that do not cause endocarditis), or serological evidence of active infection with organism consistent with IE 1

Important note: The echocardiographic minor criterion has been eliminated from the modified Duke criteria 1

Possible Infective Endocarditis

Possible IE is diagnosed when findings are suggestive but insufficient for definite diagnosis: 1, 2

• 1 major criterion AND 1 minor criterion 1, 2
• 3 minor criteria 1, 2

Rejected IE

The diagnosis is rejected when: 1

• Firm alternative diagnosis explains evidence of IE 1
• Resolution of IE syndrome with antibiotic therapy for ≤4 days 1
• No pathological evidence of IE at surgery or autopsy with antibiotic therapy for ≤4 days 1
• Does not meet criteria for possible IE 1

Critical Considerations for Prosthetic Valves and Pre-existing Heart Conditions

Prosthetic valve endocarditis (PVE) presents unique diagnostic challenges: 1

• Echocardiography is normal or inconclusive in up to 30% of PVE cases 1
• Advanced imaging (PET/CT, cardiac CT) significantly improves diagnostic sensitivity in these patients 1
• TEE is specifically recommended as the preferred modality for prosthetic valves 1

Common pitfall: Blood culture-negative endocarditis (BCNE) occurs in up to 71% of cases, often due to prior antibiotic use before cultures are obtained 4. In these cases, reliance on imaging major criteria and minor criteria becomes essential 4

Diagnostic accuracy: The Duke criteria demonstrate 80% sensitivity with high specificity across diverse populations including patients with prosthetic valves 5, though sensitivity may be lower during early clinical assessment 6