This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
A diagnosis built from several clues
Infective endocarditis is an infection of the heart valves or the inner lining of the heart. It is uncommon but serious, with in-hospital mortality of about 15 to 20%. Its signs are often vague, such as fever, fatigue and weight loss, so no single test confirms it. The Duke criteria, published in 1994 and modified by Li and colleagues in 2000, combine microbiology, imaging and clinical findings into a standard classification.
Major criteria
- Positive blood cultures: a typical organism (viridans streptococci, Streptococcus gallolyticus, the HACEK group, Staphylococcus aureus, or community-acquired enterococci with no other source) in two separate cultures; or persistently positive cultures; or a single culture positive for Coxiella burnetii, or a phase I IgG titer above 1:800.
- Evidence of endocardial involvement: a vegetation, abscess or new partial dehiscence of a prosthetic valve on echocardiography, or new valvular regurgitation.
Minor criteria
- Predisposition: a heart condition at risk (prosthetic valve, previous endocarditis, congenital or valve disease) or injection drug use.
- Fever of 38.0 °C (100.4 °F) or more.
- Vascular phenomena: arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, Janeway lesions.
- Immunologic phenomena: glomerulonephritis, Osler nodes, Roth spots, positive rheumatoid factor.
- Microbiological evidence that does not meet a major criterion.
Classification
| Result | Clinical criteria |
|---|---|
| Definite | 2 major, or 1 major and 3 minor, or 5 minor |
| Possible | 1 major and 1 minor, or 3 minor |
| Rejected | below these thresholds, a firm alternative diagnosis, or resolution with 4 days or less of antibiotics |
Worked example
A patient who injects drugs has a fever of 38.6 °C and two blood cultures growing Staphylococcus aureus, but the transthoracic echo shows no vegetation. That is 1 major and 2 minor criteria: possible endocarditis. A transesophageal echocardiogram, which detects vegetations far better, is the next step. A vegetation would add a second major criterion and make the diagnosis definite.
Updates
The 2023 Duke-ISCVID criteria and the 2023 European Society of Cardiology guidelines add PCR, cardiac CT and PET-CT, especially useful for prosthetic valves and devices. Whatever the version, a classification of possible should prompt further investigation rather than reassurance.