Criteria

Modified Duke criteria[20]

Major criteria:

  • Positive blood culture for IE:

    • Typical microorganism for IE from 2 separate blood cultures: Viridans streptococci, Streptococcus gallolyticus, HACEK group (Haemophilus spp, Aggregatibacter, Cardiobacterium hominis, Eikenella spp, and Kingella kingae), S aureus; or community-acquired enterococci, in the absence of a primary focus

    • Microorganisms consistent with IE from persistently positive blood culture results, defined as follows:

      • At least 2 positive culture results of blood samples drawn 12 hours apart

      • All of 3 or most of ≥4 separate culture samples of blood (with first and last samples drawn at least one hour apart)

      • Single positive blood culture result for Coxiella burnetii or antiphase I immunoglobulin G antibody titer >1:800

  • Evidence of endocardial involvement:

    • Echocardiogram positive for IE defined as follows:

      • Oscillating intracardiac mass on valve/supporting structures, or in the path of regurgitant jet, or on implanted material, in the absence of an alternative anatomic explanation

      • Abscess

      • New partial dehiscence of prosthetic valve

    • New valvular regurgitation (worsening or changing of pre-existing murmur not sufficient).

Minor criteria:

  • Predisposing heart condition or intravenous drug use

  • Fever over 100.4°F (38ºC)

  • Vascular phenomenon such as major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhage, Janeway lesions

  • Immunologic phenomenon:

    • Glomerulonephritis

    • Osler nodes

    • Roth spots

    • Rheumatoid factor

  • Microbiologic evidence:

    • Positive blood cultures not meeting major criteria above (excludes single positive cultures for coagulase-negative staphylococci and organisms that do not cause IE).

    • Serological evidence of infection with organism consistent with IE

Definite IE: must meet 2 major criteria, 1 major and 3 minor criteria, or 5 minor criteria.

Possible IE: must meet 1 major criterion and 1 minor criterion, or 3 minor criteria.

2023 European Society of Cardiology criteria for the diagnosis of infective endocarditis[7]​​

Major criteria:

  1. Blood culture positive for IE

    • Typical microorganisms consistent with IE from two separate blood cultures: oral streptococci, Streptococcus gallolyticus (formerly Streptococcus bovis), HACEK group, Staphylococcus aureus, Enterococcus faecalis

    • Microorganisms consistent with IE from continuously positive blood cultures:

      1. ≥2 positive blood cultures of blood samples drawn >12 hours apart

      2. All of three or a majority of ≥4 separate cultures of blood (with first and last samples drawn ≥1 hour apart)

    • Single positive blood culture for Coxiella burnetii or phase I IgG antibody titer >1:800

  2. Imaging positive for IE

    • Valvular, perivalvular/periprosthetic, and foreign material anatomic and metabolic lesions characteristic of IE detected by any of the following imaging techniques:

      1. Echocardiography (transthoracic [TTE] and transesophageal [TEE])

      2. Cardiac computed tomography (CT)

      3. 18F-FDG-positron emission tomography (PET)/CT (angiography)

      4. White blood cell single-photon emission CT (WBC SPECT)/CT

Minor criteria:

  1. Predisposing conditions (i.e., predisposing heart condition at high or intermediate risk of IE or people who inject drugs)

  2. Fever defined as temperature >100.4°F (>38°C)

  3. Embolic vascular dissemination (including those asymptomatic detected by imaging only):

    • Major systemic and pulmonary emboli/infarcts and abscesses

    • Hematogenous osteoarticular septic complications (i.e., spondylodiscitis)

    • Mycotic aneurysms

    • Intracranial ischemic/hemorrhagic lesions

    • Conjunctival hemorrhages

    • Janeway lesions

  4. Immunologic phenomena:

    • Glomerulonephritis

    • Osler nodes and Roth spots

    • Rheumatoid factor

  5. Microbiologic evidence:

    • Positive blood culture but does not meet a major criterion as noted above

    • Serologic evidence of active infection with organism consistent with IE

These criteria are used to classify patients with suspected IE as “definite”, “possible”, or “rejected”.

  • Definite IE must meet:

    • 2 major criteria

    • 1 major criterion and at least 3 minor criteria

    • 5 minor criteria

  • Possible IE must meet:

    • 1 major criterion and 1 or 2 minor criteria

    • 3-4 minor criteria

  • Rejected IE

    • Does not meet criteria for definite or possible at admission with or without a firm alternative diagnosis

If the diagnosis of IE is classified as “possible” or “rejected” but there is still a high level of clinical suspicion:

  • Repeat blood cultures

  • Repeat echocardiography within 5-7 days

  • Perform cardiac CT angiography (CTA) to diagnose valvular lesions

  • Consider other imaging modalities:

    • Brain or whole-body imaging (magnetic resonance imaging [MRI], CT, PET/CT, or WBC SPECT) to detect distant lesions in suspected native valve IE

    • WBC SPECT and brain or whole-body imaging (MRI, CT, PET/CT, or WBC SPECT) to detect distant lesions in suspected prosthetic

    • PET/CT to detect pocket infection or pulmonary embolism in patients with cardiac device-related IE

If the diagnosis of IE is confirmed “definite”, further imaging is still warranted:

  • Cardiac CTA if there are suspected paravalvular complications and TEE is inconclusive

  • Brain and whole-body imaging (CT, 18F-FDG-PET/CTA, and/or MRI) for all patients with confirmed IE, in particular if there are symptoms suggestive of extracardiac complications

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