Table 1 Modified Duke criteria for diagnosis of infective endocarditis

Major criteria

 - Typical microorganism consistent with IE from two separate blood cultures: viridans-group streptococci, Streptococcus bovis, HACEK group, Staphylococcus aureus or community-acquired enterococci, in the absence of a primary focus

 OR

 - Microorganisms consistent with IE from persistently positive blood cultures defined as:

  . Two positive cultures of blood samples drawn >12 h apart, or

  . All of three or a majority of four separate cultures of blood (with first and last sample drawn 1 h apart)

 OR

 - Coxiella burnetii detected by at least one positive blood culture or antiphase I IgG antibody titre >1:800

 OR

 - Positive echocardiogram showing vegetation, abscess, new valvular regurgitation or new dehiscence of prosthetic valves.

Minor criteria

 • Predisposing heart disease, drug injection

 • Fever: temperature >38°

 • Vascular phenomena: arterial emboli, splenomegaly, mycotic aneurysm, conjunctival haemorrhages, petechiae or purpura

 • Immunological phenomena: glomerulonephritis, Osler’s nodes, Roth spots or rheumatoid factor

 • Microbiological evidence not fitting major criteria

Definite IE

 • Two major criteria

 OR

 • One major and three minor criteria

 OR

 • Five minor criteria

Possible IE

 • One major criterion and one minor criterion

 OR

 • Three minor criteria