What are the diagnostic criteria for Infective Endocarditis (IE)?

From the Guidelines

The diagnosis of infective endocarditis relies on the modified Duke criteria, which categorizes patients as having definite, possible, or rejected endocarditis based on major and minor criteria. Major criteria include positive blood cultures for typical endocarditis organisms (such as viridans streptococci, Staphylococcus aureus, HACEK group, or community-acquired enterococci) from two separate blood cultures, or persistently positive blood cultures for other organisms 1. The second major criterion is evidence of endocardial involvement, demonstrated by echocardiography showing a vegetation, abscess, or new valvular regurgitation, or a new partial dehiscence of a prosthetic valve. Minor criteria include predisposing heart conditions, intravenous drug use, fever above 38°C, vascular phenomena (like septic emboli or Janeway lesions), immunologic phenomena (such as Osler nodes, Roth spots, or glomerulonephritis), and microbiological evidence not meeting major criteria.

Some key points to consider when applying the modified Duke criteria include:

• Definite endocarditis requires either two major criteria, one major plus three minor criteria, or five minor criteria 1.
• Possible endocarditis is diagnosed with one major plus one minor criterion, or three minor criteria 1.
• When evaluating a patient with suspected endocarditis, obtaining at least three sets of blood cultures before starting antibiotics is crucial, and both transthoracic and transesophageal echocardiography should be considered, as the latter has higher sensitivity for detecting vegetations and abscesses, particularly with prosthetic valves 1.
• The use of case definitions to establish a diagnosis of IE should not replace clinical judgment, and the recently modified Duke criteria have been useful in both epidemiological and clinical trials and in individual patient management 1.

It's also important to note that the diagnosis of IE must be made as soon as possible to initiate appropriate empirical antibiotic therapy and to identify patients at high risk for complications who may be best managed by early surgery 1. In cases with a high suspicion of IE based on either the clinical picture or the patient’s risk factor profile, the presumption of IE often is made before blood culture results are available, and identification of vegetations and incremental valvular insufficiency with echocardiography often completes the diagnostic criteria for IE and affects the duration of therapy 1.

From the Research

Diagnostic Criteria for Infective Endocarditis (IE)

The diagnostic criteria for Infective Endocarditis (IE) are based on several factors, including blood culture results, echocardiographic findings, and clinical presentation.

• The modified Duke criteria are widely used for the diagnosis of IE, which integrate factors predisposing patients to the development of IE, the blood-culture isolates and persistence of bacteremia, and echocardiographic findings, along with other clinical and laboratory information 2.
• The Duke criteria define two "major criteria" (typical blood culture and positive echocardiogram) and six "minor criteria" (predisposition, fever, vascular phenomena, immunologic phenomena, suggestive echocardiogram, and suggestive microbiologic findings) 3.
• The diagnostic criteria include:
  • Major criteria:
    • Typical blood culture (e.g., Staphylococcus aureus, Streptococcus viridans)
    • Positive echocardiogram (e.g., vegetation, abscess)
  • Minor criteria:
    • Predisposition (e.g., heart condition, intravenous drug use)
    • Fever
    • Vascular phenomena (e.g., emboli, Janeway lesions)
    • Immunologic phenomena (e.g., glomerulonephritis, rheumatoid factor)
    • Suggestive echocardiogram (e.g., thickened valve, prosthetic valve)
    • Suggestive microbiologic findings (e.g., positive blood culture, serology)
• The 2023 Duke-International Society of Cardiovascular Infectious Diseases (ISCVID) diagnostic criteria have been recently proposed, which include revised microbiology criteria, positron emission tomography-computed tomography, and cardiac implanted electronic devices 4.
• The use of transesophageal echocardiography has a sensitivity of 76-100% for detecting vegetation, whereas transthoracic echocardiography has a sensitivity of 50-60% 2.
• Blood cultures remain the standard test for microbial diagnosis, with directed serological testing (e.g., Q fever serology, Bartonella serology) in culture-negative cases 5.
• Histopathology and molecular diagnostics (e.g., 16S rRNA gene PCR/sequencing, Tropheryma whipplei PCR) may be applied to resected valves to aid in diagnosis 5.
• The Duke criteria have been shown to be more sensitive and specific than the von Reyn criteria, and are considered a standard reference for diagnosing infective endocarditis 6.