Table 2. Modified Duke criteria for the diagnosis of infective endocarditis.

Pathological criteria Microorganisms on histology or culture of a vegetation or intra-cardiac abscess Evidence of lesions: vegetation or intra-cardiac access showing active endocarditis on histology Major clinical criteria 1. Blood cultures positive for infective endocarditis Typical microorganisms consistent with infective endocarditis from two separate blood cultures: - Staphylococcus aureus, viridans streptococci, Streptococcus bovis, HACEK group, or community-acquired enterococci in the absence of a primary focus OR Microorganisms consistent with infective endocarditis from persistently positive blood cultures: - At least two positive blood cultures from samples drawn more than 12 hours apart or all of three or most of at least four separate cultures of blood (with first and last sample more than one hour apart) OR Single positive blood culture for Coxiella burnetii or phase 1 IgG antibody titre greater than 1:800 2. Evidence of endocardial involvement Echocardiography positive for infective endocarditis - Defined by presence of a vegetation, abscess or new partial dehiscence of a prosthetic valve New valvular regurgitation - Note: increase or change in pre-existing murmur is not sufficient. Minor clinical criteria 1. Predisposition: predisposing heart condition and intravenous drug use 2. Fever: temperature >38°C 3. Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intra-cranial haemorrhages, conjunctival haemorrhages, and Janeway lesions 4. Immunological phenomena: glomerulonephritis, Osler’s nodes, Roth spots, and rheumatoid factor 5. Microbiological evidence: positive blood culture that does not meet a major criterion or serological evidence of active infection with organism consistent with infective endocarditis Diagnosis of endocarditis is definite in the presence of one pathological criterion, two major criteria, one major and three minor criteria, or five minor criteria. Diagnosis of infective endocarditis is possible in the presence of one major and one minor criterion or three minor criteria. Modified Duke criteria were originally published by Li and colleagues 11.