The Modified Duke Criteria are used to diagnose infective endocarditis(IE). The criteria are divided into major and minor criteria.

Major Criteria:

1. Positive blood culture for IE:
   a. Typical microorganisms for IE (e.g., Streptococcus viridans, Streptococcus gallolyticus [formerly known as Streptococcus bovis], HACEK group, Staphylococcus aureus, or community-acquired Enterococcus) from two separate blood cultures.
   b. Microorganisms consistent with IE from persistently positive blood cultures, defined as ≥2 positive cultures of blood samples drawn ≥12 hours apart.
   c. Positive blood culture for IE and evidence of recent intravascular catheter-related Staphylococcus aureus bacteremia.
2. Evidence of endocardial involvement:
   a. Positive echocardiogram for IE (e.g., vegetation, abscess, or new prosthetic dehiscence).

Minor Criteria:

1. Predisposing heart condition or intravenous drug use.
2. Fever, temperature ≥38°C.
3. Vascular phenomena, major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, and Janeway lesions.
4. Immunologic phenomena: glomerulonephritis, Osler’s nodes, Roth spots, and rheumatoid factor.
5. Microbiological evidence: positive blood culture but does not meet a major criterion as noted above or serological evidence of active infection with organism consistent with IE.

Definitive IE:

To diagnose definitive IE, patients must meet one of the following conditions:

1. Two major criteria.
2. One major criterion and three minor criteria.
3. Five minor criteria.

Possible IE:

Patients with one major criterion and one or two minor criteria, or three minor criteria, are considered to have possible IE.