Endocarditis

Introduction

Spontaneous bacterial endocarditis (SBE or infective endocarditis) is an infectious condition in which the cardiac valves or endocardial surface become seeded with a pathogenic organism. While this is most commonly bacterial, fungal endocarditis is becoming more frequent due to increasing populations that are immunocompromised.

Diagnosis

The Duke criteria for endocarditis are summarized below. These were originally proposed in 1994 to help establish the diagnosis of endocarditis. Two major and one minor criteria are needed to diagnosis endocarditis. Alternatively, one major and 3 minor can be present.

Major criteria:

1. Positive blood cultures defined as below:

Typical organism isolated from two separate blood cultures

  • Streptococcus viridans species or Streptococcus gallolyticus
  • HACEK group organisms
  • Staphylococcus aureus
  • Community-acquired enterococci in the absence of another focus

Persistently positive blood cultures from organism not mentioned above

  • Two blood cultures positive drawn 12 hours apart
  • Three of four blood cultures positive even if drawn together

2. Evidence of endocardial involvement

Echocardiographic evidence of endocarditis

  • Vegetation defined as “oscillating intracardiac mass on a valve or supporting structure, in the path of a regurgitant jet, or on implanted material”.
  • Intracardiac abscess
  • Dehiscence of a prosthetic heart valve

New valvular regurgitation (new murmur does not meet criteria)

Minor criteria:

Predisposing heart condition or IV drug use
Fever (38.0 C or 100.4 F)
Vascular phenomena

  • Arterial embolism
  • Septic pulmonary infarctions
  • Mycotic aneurysm
  • Intracranial hemorrhage or conjunctival hemorrhages
  • Janeway lesions

Immunologic phenomena

  • Glomerulonephritis
  • Osler’s nodes
  • Roth spots
  • Positive rheumatoid factor

Microbiologic evidence (positive blood cultures not meeting major criteria)

Treatment

Treatment includes appropriate antibiotic therapy and supportive care.

The indications for valve replacement in patients with endocarditis are:

  1. Congestive heart failure from valvular regurgitation
  2. Failure of antibiotic therapy to successfully suppress the infection or infection with difficult to treat organisms (fungal, Pseudomonas, Brucella, drug-resistant organisms)
  3. Valvular annular abscess
  4. Peripheral embolism of vegetation
  5. Size of vegetation > 1.0 cm

Miscellaneous

Aortic annular abscess can occur as a complication of endocarditis and can manifest electrically as a first degree AV block on the ECG.

Streptococcus bovis endocarditis is associated with colon cancer.