Infective endocarditis

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Infective endocarditis, abbreviated IE, is an uncommon disease of the heart lining/heart valves.

Bacterial endocarditis and subacute bacterial endocarditis (abbreviated SBE) redirect here.

General

  • Infection of the endocardium - often involves the valves (which are covered by endocardium).
  • Before the time of antibiotics -- 100% fatal.

Organisms

Most common organism overall:

  • Staphylococcus aureus.[1]

Organisms associated with particular clinical scenarios:

  • IV drug users / normal valves = Staphylococcus aureus.[2]
  • Previously damaged valve = Streptococcus viridans.
  • Prosthetic valves = Staphylococcus epidermidis.[3]

Organisms that less commonly cause IE are known as the HACEK group:[2]

  • Haemophilus (Haemophilus parainfluenzae, Haemophilus aphrophilus, Haemophilus paraphrophilus).
  • Actinobacillus (Actinobacillus actinomycetemcomitans, Aggregatibacter aphrophilus).
  • Cardiobacterium hominis.
  • Eikenella corrodens. †
  • Kingella (Kingella kingae).

Notes:

  • † Enterococci are not included in this list but are lumped with the HACEK organisms.[2]

Others:

  • Stenotrophomonas maltophilia (previously Pseudomonas maltophilia) - Gram-negative bacillus,[4] rarely causes endocarditis,[5] high mortality.[6]

Clinical

  • Diagnosed (clinically) using the Duke criteria.[7][8]
    • Positive blood cultures.
    • Cardiac involvement - vegetation.
    • +/-Febrile.

Subdivided into:

  1. Acute IE.
    • Classically due to Staphylococcus aureus.
  2. Subacute IE.
    • Classically due to Streptococcus viridans.

Treatment:[9]

  • Usually medical management.[10]
  • Valve replacement.
  • Valve repair.
  • Valvectomy - for tricuspid valve.

Gross

  • Location - left-sided involvement (mitral, aortic) more common than right-sided involvement (pulmonic, tricuspid).
    • This is reversed in IV drug users.[2][11]
  • +/-Valvular destruction.
    • More common in acute IE.
  • +/-Distant emboli, e.g. splenic infarct.
    • More common in acute IE.
  • +/-Valvular vegetations.
    • Irregular ball of loosely adherent tissue - dull, irregular surface.
    • On the ventricular aspect in aortic valve IE.
    • Larger in acute IE.

Image

  • Infective endocarditis.

www:

Microscopic

Features:

  • Inflammatory infiltrate (key feature @ low power):
    • +/-Plasma cells - subacute.
    • +/-Neutrophils - typically abundant, may be rare in subacute.[12]
  • Microorganisms - key feature (diagnostic).
    • Hard to see (even at high power).

DDx:

Stains

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TRICUSPID VALVE, VALVECTOMY:
- FRAGMENTS OF VALVE WITH INFECTIVE ENDOCARDITIS -- ABUNDANT COCCI
  ORGANISMS IDENTIFIED.
- THIN RIM OF CARDIAC MUSCLE WITHOUT APPARENT PATHOLOGY.

MITRAL VALVE, VALVE REPLACEMENT:
- FRAGMENTS OF VALVE WITH INFECTIVE ENDOCARDITIS -- ABUNDANT COCCI
  ORGANISMS IDENTIFIED.

No microorganisms

AORTIC VALVE (BICUSPID), VALVE REPLACEMENT:
- BICUSPID VALVE WITH CALCIFIC AORTIC STENOSIS AND MILD ENDOCARDITIS.
- NO MICROORGANISMS APPARENT.

Micro

The sections show valve tissue with an attached vegetation with abundant cocci organisms and neutrophils. No calcification is apparent.

No microorganisms

The sections show valve tissue with marked calcification, scattered neutrophils and plasma cells. No microorganisms are identified with routine stains.

See also

References

  1. ↑ Petti, CA.; Fowler, VG. (Jun 2002). "Staphylococcus aureus bacteremia and endocarditis.". Infect Dis Clin North Am 16 (2): 413-35, x-xi. PMID 12092480.
  2. ↑ 2.0 2.1 2.2 2.3 Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 298. ISBN 978-1416054542.
  3. ↑ Alonso-Valle, H.; Fariñas-Alvarez, C.; García-Palomo, JD.; Bernal, JM.; Martín-Durán, R.; Gutiérrez Díez, JF.; Revuelta, JM.; Fariñas, MC. (Apr 2010). "Clinical course and predictors of death in prosthetic valve endocarditis over a 20-year period.". J Thorac Cardiovasc Surg 139 (4): 887-93. doi:10.1016/j.jtcvs.2009.05.042. PMID 19660339.
  4. ↑ Gautam, V.; Ray, P.; Vandamme, P.; Chatterjee, SS.; Das, A.; Sharma, K.; Rana, S.; Garg, RK. et al. "Identification of lysine positive non-fermenting gram negative bacilli (Stenotrophomonas maltophilia and Burkholderia cepacia complex).". Indian J Med Microbiol 27 (2): 128-33. doi:10.4103/0255-0857.49425. PMID 19384035.
  5. ↑ Carrillo-Córdova, JR.; Amezcua-Guerra, LM.. "Autoimmunity as a possible predisposing factor for Stenotrophomonas maltophilia endocarditis.". Arch Cardiol Mex 82 (3): 204-7. doi:10.1016/j.acmx.2012.03.001. PMID 23021356.
  6. ↑ Fontenier, G.; Freschard, R.; Mourot, M. (Sep 1975). "Study of the corrosion in vitro and in vivo of magnesium amodes involved in an implantable bioelectric battery.". Med Biol Eng 13 (5): 683-9. PMID 1186330.
  7. ↑ http://www.medcalc.com/endocarditis.html
  8. ↑ Durack DT, Lukes AS, Bright DK (March 1994). "New criteria for diagnosis of infective endocarditis: utilization of specific echocardiographic findings. Duke Endocarditis Service". Am. J. Med. 96 (3): 200-9. PMID 8154507.
  9. ↑ Gaca, JG.; Sheng, S.; Daneshmand, M.; Rankin, JS.; Williams, ML.; O'Brien, SM.; Gammie, JS. (Aug 2013). "Current Outcomes for Tricuspid Valve Infective Endocarditis Surgery in North America.". Ann Thorac Surg. doi:10.1016/j.athoracsur.2013.05.046. PMID 23968767.
  10. ↑ Chait, RD.; Midwall, J. (Feb 2006). "Tricuspid valvectomy: long-term survival and surgical options.". Clin Cardiol 29 (2): 83-4. PMID 16506645.
  11. ↑ Mathura, KC.; Thapa, N.; Rauniyar, A.; Magar, A.; Gurubacharya, DL.; Karki, DB.. "Injection drug use and tricuspid valve endocarditis.". Kathmandu Univ Med J (KUMJ) 3 (1): 84-6. PMID 16401952.
  12. ↑ URL: http://emedicine.medscape.com/article/216650-overview#a0104. Accessed on: 26 November 2013.
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