1) Microorganisms demonstrated by culture or on histologic examination of a vegetation, a vegetation that has embolized, or an intracardiac abscess specimen; or

2) Pathologic lesions; vegetation or intracardiac abscess confirmed by histologic examination showing active endocarditis.

Major criteria

1) Blood cultures positive for IE:

a) Typical microorganisms consistent with IE from 2 separate blood cultures: Viridans-group streptococci, Streptococcus gallolyticus (formerly bovis), HACEK group, Staphylococcus aureus; or community-acquired enterococci in the absence of a primary focus; or

b) Microorganisms consistent with IE from persistently positive blood cultures: ≥2 positive blood cultures of samples drawn >12 h apart or all of 3 or a majority of ≥4 separate cultures of blood (with first and last samples drawn ≥1 h apart); or

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

2) Imaging studies positive for IE:

a) Echocardiography positive for IE: Vegetation; abscess, pseudoaneurysm, intracardiac fistula; valvular perforation or aneurysm; new partial dehiscence of a prosthetic valve.

b) Abnormal activity around the site of prosthetic valve implantation detected by 18F-FDG PET/CT (only if the prosthesis was implanted for >3 months) or radiolabeled leukocyte SPECT/CT.

c) Definite paravalvular lesions on cardiac CT.

Minor criteria

1) Predisposition, such as predisposing heart condition or injection drug use.

2) Fever defined as temperature >38°C.

3) Vascular phenomena (including those detected by imaging only): Major arterial emboli, septic pulmonary infarcts, infectious (mycotic) aneurysm, intracranial hemorrhage, conjunctival hemorrhages, and Janeway lesions.

4) Immunologic phenomena: Glomerulonephritis, Osler nodes, Roth spots, and rheumatoid factor.

5) Microbiologic evidence: Positive blood culture but not meeting a major criterion as noted above or serologic evidence of active infection with an organism consistent with IE.

Definite IE: 2 major criteria; 1 major criterion and 3 minor criteria; or 5 minor criteria.

Possible IE: 1 major criterion and 1 minor criterion; or 3 minor criteria.

Rejected IE:

1) Firm alternative diagnosis; or

2) Resolution of symptoms suggesting IE with antibiotic therapy for ≤4 days; or

3) No pathologic evidence of IE at surgery or autopsy with antibiotic therapy for ≤4 days; or

4) Not fulfilling the criteria for possible IE, as defined above.