Infective endocarditis resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Farman Khan, MD, MRCP [2]

Definition

Infection of the endothelium of the heart including but not limited to the valves. It can be either acute or subacute. Acute bacterial endocarditis is defined as Infection of normal heart valves with a virulent organism like S. aureus, Group A or other beta-hemolytic streptococci, Streptococcus pneumoniae. Subacute bacterial endocarditis is an indolent infection of abnormal valves with less virulent organism like Streptococcus viridans.

Criteria	Definite Infective Endocarditis According to Modified Duke Criteria
Pathological Criteria	Microorganisms demonstrated by culture or histological examination of a vegetation Pathological lesions; vegetation or intracardiac abscess confirmed by histological examination showing active endocarditis
Clinical Criteria	2 major criteria; or 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	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

Definite Infective Endocarditis According to Modified Duke Criteria

Pathological Criteria ❑ Microorganisms demonstrated by culture or histological examination of a vegetation ❑ Pathological lesions; vegetation or intracardiac abscess confirmed by histological examination showing active endocarditis Clinical Criteria ❑ 2 major criteria; or ❑ 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 ❑ 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

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Endocarditis can be a life-threatening condition if it is left untreated, and it must be treated as such irrespective of the causes.

Common Causes

• Streptococcus viridans
• Staphylococci
• Enterococcus.

Management

Diagnostic Criteria

Shown below is an algorithm depicting the diagnostic criteria of infective endocarditis based on the 2005 American Heart Association (AHA) technical review and medical position statement regarding guidelines on infective endocarditis.

Duke Criteria

The Duke Clinical Criteria for Infective Endocarditis requires either: ❑ Two major criteria, or ❑ One major and three minor criteria, or ❑ Five minor criteria

Major Criteria

Minor criteria

Positive Blood Culture for Infective Endocarditis Typical microorganism consistent with infective endocarditis from 2 separate blood cultures, as noted below: ❑ Viridans streptococci, streptococcus bovis ❑ HACEK group ❑ Community-acquired staphylococcus aureus ❑Enterococci, in the absence of a primary focus, or Microorganisms consistent with infective endocarditis from persistently positive blood cultures defined as: ❑ 2 positive cultures of blood samples drawn >12 hours apart, or ❑ All of 3 or a majority of 4 separate cultures of blood (with first and last sample drawn 1 hour apart) Echocardiographic evidence of endocardial involvement ❑ 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, or ❑ Abscess, or ❑ New partial dehiscence of prosthetic valve, or ❑ New valvular regurgitation (worsening or changing of preexisting murmur not sufficient)

Predisposition: ❑ Predisposing heart condition or intravenous drug use Fever: ❑ Temperature > 38.0° C (100.4° F) Vascular phenomena: ❑ Major arterial emboli ❑ Septic pulmonary infarcts ❑ Mycotic aneurysm ❑ Intracranial hemorrhage ❑ Conjunctival hemorrhage ❑ Janeway lesions Immunologic phenomena: ❑ Glomerulonephritis ❑ Osler's nodes ❑ Roth spots ❑ Rheumatoid factor Microbiological evidence: ❑ Positive blood culture but does not meet a major criterion as noted above ❑ Serological evidence of active infection with organism consistent with infectious endocarditis Echocardiographic findings: ❑ Consistent with infectious endocarditis but do not meet a major criterion as noted above

Diagnostic approach

Shown below is an algorithm summarizing the approach to infective endocarditis.

A1 Box 1 in Row 1

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C1 Box 1 in Row 3

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References

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