Guidelines for Antimicrobial Use

Diagnosis:

Clinical suspicion, blood culture and echocardiography remain the cornerstone of diagnosis of IE. Modified Duke’s Criteria which includes major and minor criteria is useful in the diagnosis of IE (Table 13.2). Presence of 2 major criteria or 1 major and 3 minor criteria or 5 minor criteria is suggestive of definite IE while presence of 1 major and 1 minor or 3 minor criteria is suggestive of possible IE. Rejected IE is firm alternative diagnosis explaining evidence of IE; or resolution of IE syndrome with antibiotic therapy for ≤4 days; or no pathological evidence of IE at surgery or autopsy with antibiotic therapy for ≤4 days; or does not meet criteria for possible IE as above.

Modified Duke’s Criteria for the Diagnosis of IE

Criteria	Features
Major criteria	Blood culture positive for IE Typical microorganisms consistent with IE from 2 separate blood cultures: Viridans 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 follows: at least 2 positive cultures of blood samples drawn >12 h apart or all 3 or a majority of ≥4 separate cultures of blood (with first and last sample drawn at least 1 h apart) Single positive blood culture for Coxiella burnetii* or anti–phase 1 IgG antibody titer ≥1:800 Evidence of endocardial involvement Echocardiogram positive for IE (TEE recommended for patients with prosthetic valves, rated at least possible IE by clinical criteria, or complicated IE [paravalvular abscess]; TTE as first test in other patients)** defined as follows: oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets, or on implanted material in the absence of an alternative anatomic explanation; abscess; or new partial dehiscence of prosthetic valve or new valvular regurgitation (worsening or changing or pre-existing murmur not sufficient)
Minor criteria	Predisposition, predisposing heart condition, or IDU Fever, temperature >38°C Vascular phenomena, major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, and Janeway lesions Immunological phenomena glomerulonephritis, Osler nodes, Roth spots, and rheumatoid factor Microbiological evidence: positive blood culture but does not meet a major criterion as noted above (excludes single positive cultures for coagulase negative staphylococci and organisms that do not cause endocarditis) or serological evidence of active infection with organism consistent with IE

Criteria

Features

Major criteria

Blood culture positive for IE

Typical microorganisms consistent with IE from 2 separate blood cultures:
Viridans 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 follows: at least 2 positive cultures of blood samples drawn >12 h apart or all 3 or a majority of ≥4 separate cultures of blood (with first and last sample drawn at least 1 h apart)
Single positive blood culture for Coxiella burnetii or anti–phase 1 IgG
antibody titer ≥1:800

Evidence of endocardial involvement

Echocardiogram positive for IE (TEE recommended for patients with
prosthetic valves, rated at least possible IE by clinical criteria, or complicated IE [paravalvular abscess]; TTE as first test in other patients) defined as follows: oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets, or on implanted material in the absence of an alternative anatomic explanation; abscess; or new partial dehiscence of prosthetic valve or new valvular regurgitation (worsening or changing or pre-existing murmur not sufficient)

Minor criteria

Predisposition, predisposing heart condition, or IDU
Fever, temperature >38°C
Vascular phenomena, major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, and Janeway lesions
Immunological phenomena glomerulonephritis, Osler nodes, Roth spots, and rheumatoid factor
Microbiological evidence: positive blood culture but does not meet a major criterion as noted above (excludes single positive cultures for coagulase negative staphylococci and organisms that do not cause endocarditis) or serological evidence of active infection with organism consistent with IE

HACEK indicates Haemophilus species, Aggregatibacter species, cardiobacterium hominis, Eikenella corrodens, and Kingella species; IDU, injection drug use; IE, infective endocarditis; IgG, immunoglobulin G; TEE transesophageal echocardiography; and TTE, transthoracic echocardiography.