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Source: Veverka A, Odle BL, Kyle JA. Infective endocarditis. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. Accessed January 10, 2017.


  • Inflammation of endocardium, membrane lining chambers of heart and covering cusps of heart valves.

  • Infective endocarditis (IE) refers to infection of heart valves by microorganisms, primarily bacteria.

    • Acute bacterial endocarditis is fulminating infection associated with high fevers, systemic toxicity, and death within days to weeks if untreated.

    • Subacute infectious endocarditis a more indolent infection, usually occurring in setting of prior valvular heart disease.


  • Majority of IE cases due to streptococci, staphylococci, and enterococci (Table 1).

TABLE 1.aEtiologic Organisms in Infective Endocarditisa


  • Most commonly develops via hematogenous spread.

    • Endothelial surface of heart damaged.

    • Platelet and fibrin deposition occurs on abnormal epithelial surface.

    • Organisms colonize endocardial surface.

      • Bacteremia results from trauma to mucosal surface with high concentration of resident bacteria (eg, oral cavity, gastrointestinal [GI] tract).

    • “Vegetation” of fibrin, platelets, and bacteria form on endothelial surface.

      • Bacteria protected from antibiotics and host defenses.

      • Valvular tissue may be destroyed.

      • Abscesses may develop in valve.

      • Friable vegetation (septic emboli) may travel to other organs, resulting in infarction or abscesses.


  • Antimicrobial prophylaxis used to prevent IE in patients at high risk undergoing procedures that cause transient bacteremia.

  • Issues to consider in prevention.

    • Types of patients at risk.

      • Prosthetic cardiac valves.

      • Previous IE

      • Congenital heart disease.

      • Cardiac transplant patient who develops cardiac valvulopathy.

    • Procedures causing bacteremia.

      • Dental procedures involving manipulation of gingival tissue of periapical region of teeth or perforation of oral mucosa.

    • Organisms most likely to cause IE

    • Pharmacokinetics, spectrum, cost, and ease of administration of available agents.


  • Presence of prosthetic valve (highest risk)

  • Previous endocarditis (highest risk)

  • Healthcare-related exposure (high risk)

  • Congenital heart disease.

  • Chronic intravenous access.

  • Acquired valvular dysfunction.

  • Hypertrophic cardiomyopathy.

  • Mitral valve prolapse with regurgitation.

  • Cardiac implantable device.

  • Chronic heart failure.

  • Age >50 years.

  • History of IV drug abuse.

  • Diabetes.

  • Long-term hemodialysis.

  • Poor dental hygiene.


  • Highly variable and ...

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