Infective Endocarditis Differential Diagnoses

Updated: Jan 21, 2021
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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Diagnostic Considerations

Definitive diagnosis of IE is generally made by using the Duke criteria.

Duke diagnostic criteria

Durack and colleagues developed diagnostic criteria that combine the clinical, microbiologic, pathologic, and echocardiographic characteristics of a specific case. [4]

Major blood culture criteria include the following:

  • Two blood cultures positive for organisms typically found in patients with IE (ie, S viridans, Streptococcus bovis, a HACEK group organism, community-acquired S aureus, or enterococci in the absence of a primary focus)

  • Blood cultures persistently positive for 1 of the above organisms from cultures drawn more than 12 hours apart

  • Three or more separate blood cultures drawn at least 1 hour apart

Major echocardiographic criteria include the following:

  • Echocardiogram positive for IE, documented by an oscillating intracardiac mass on a valve or on supporting structures, in the path of regurgitant jets, or on implanted material in the absence of an alternative anatomical explanation

  • Myocardial abscess

  • Development of partial dehiscence of a prosthetic valve

  • New-onset valvular regurgitation

Minor criteria include the following:

  • Predisposing heart condition or intravenous drug use

  • Fever of 38°C (100.4°F) or higher

  • Vascular phenomenon, including major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhage, or Janeway lesions

  • Immunologic phenomenon such as glomerulonephritis, Osler nodes, Roth spots, and rheumatoid factor

  • Positive blood culture results not meeting major criteria or serologic evidence of active infection with an organism consistent with IE (eg, Brucella, C burnetii [ie, Q fever], Legionella)

  • Echocardiogram results consistent with IE but not meeting major echocardiographic criteria

Definitive pathologic diagnosis is established by demonstrating microorganisms, by culture or histology, in vegetations removed by surgery, embolectomy, or drainage of an intracardiac abscess. Alternatively, a definitive clinical diagnosis is made on the basis of the presence of 2 major criteria, 1 major criterion and 3 minor criteria, or 5 minor criteria.

A diagnosis of possible IE is made when findings consistent with IE fall short of the criteria for definite IE but do not meet the criteria for rejection.

Rejection criteria for the diagnosis of IE are as follows:

  • The presence of a firm alternative diagnosis of the manifestations of endocarditis

  • Resolution of manifestations of endocarditis after 4 or fewer days of antimicrobial therapy

  • No pathologic evidence of IE at surgery or autopsy after 4 or fewer days of antimicrobial therapy

These criteria may, at times, overdiagnose IE and may not be as applicable in patients with subacute disease.

Other problems to be considered include the following:

  • Thrombotic nonbacterial endocarditis

  • Vasculitis

  • Temporal arteritis

  • Marantic endocarditis

  • Connective tissue disease

  • Fever of unknown origin 

  • Intra-abdominal infections

  • Septic pulmonary infarction

  • Tricuspid regurgitation

Differential Diagnoses