Subacute bacterial endocarditis

Subacute bacterial endocarditis, abbreviated SBE, is a type of endocarditis (more specifically, infective endocarditis).[5] Subacute bacterial endocarditis can be considered a form of type III hypersensitivity.[6]

Subacute bacterial endocarditis
Other namesEndocarditis lenta
Vegetation of tricuspid valve by ECHO
SpecialtyCardiology 
SymptomsMalaise, weakness[1]
CausesStreptococcus mutans, mitis, sanguis or milleri bacteria[2][3]
Diagnostic methodBlood culture specimens over 24-hour period/analysis[4]
TreatmentIntravenous penicillin[2]

Signs and symptoms

Among the signs of subacute bacterial endocarditis are:[1]

Causes
Streptococci

It is usually caused by a form of Viridans group streptococcus bacteria that normally live in the mouth[3] (Streptococcus mutans, mitis, sanguis or milleri).[2]

Other strains of streptococci can cause subacute endocarditis as well. These include streptococcus intermedius, which can cause acute or subacute infection (about 15% of cases pertaining to infective endocarditis).[7]

Enterococci from urinary tract infections and coagulase negative staphylococci can also be causative agents.[5]

Mechanism

The mechanism of subacute bacterial endocarditis could be due to malformed stenotic valves which in the company of bacteremia, become infected, via adhesion and subsequent colonization of the surface area. This causes an inflammatory response, with recruitment of matrix metalloproteinases, and destruction of collagen.[8]

Underlying structural valve disease is usually present in patients before developing subacute endocarditis, and is less likely to lead to septic emboli than is acute endocarditis, but subacute endocarditis has a relatively slow process of infection and, if left untreated, can worsen for up to one year before it is fatal. In cases of subacute bacterial endocarditis, the causative organism (streptococcus viridans) needs a previous heart valve disease to colonize.[9] On the other hand, in cases of acute bacterial endocarditis, the organism can colonize on the healthy heart valve, causing the disease.[10]

Diagnosis

Diagnosis of subacute bacterial endocarditis can be done by collecting three blood culture specimens over a 24-hour period for analysis,[4] also it can usually be indicated by the existence of:

Treatment
Aminoglycoside

The standard treatment is with a minimum of four weeks of high-dose intravenous penicillin with an aminoglycoside such as gentamicin. The use of high-dose antibiotics is largely based upon animal models.[2]

Leo Loewe of Brooklyn Jewish Hospital was the first to successfully treat subacute bacterial endocarditis with penicillin. Loewe reported at the time seven cases of subacute bacterial endocarditis in 1944.[14]

See also

References
  1. Jefferson, James W. (2012-12-06). Neuropsychiatric Features of Medical Disorders. Springer Science & Business Media. p. 28. ISBN 9781468439205.
  2. Verhagen, DW; Vedder, AC; Speelman, P; van der Meer, JT (2006). "Antimicrobial treatment of infective endocarditis caused by viridans streptococci highly susceptible to penicillin: historic overview and future considerations". The Journal of Antimicrobial Chemotherapy. 57 (5): 819–24. doi:10.1093/jac/dkl087. PMID 16549513.
  3. deWit, Susan C.; Kumagai, Candice K. (2014-04-14). Medical-Surgical Nursing: Concepts & Practice. Elsevier Health Sciences. p. 101. ISBN 9780323293211.
  4. Engelkirk, Paul G.; Duben-Engelkirk, Janet L. (2008-01-01). Laboratory Diagnosis of Infectious Diseases: Essentials of Diagnostic Microbiology. Lippincott Williams & Wilkins. p. 446. ISBN 9780781797016.
  5. "Infective Endocarditis. Information; prevention of endocarditis | Patient". Patient. Retrieved 2015-08-28.
  6. Keogan, Mary; Wallace, Eleanor M.; O'Leary, Paula (2006-04-18). Concise Clinical Immunology for Healthcare Professionals. Routledge. p. 106. ISBN 9781134428021.
  7. "Endocarditis". The Lecturio Medical Concept Library. Retrieved 18 July 2021.
  8. Pathology of Infectious Endocarditis at eMedicine
  9. Pommerville, Jeffrey C. (2012-01-15). Alcamo's Fundamentals of Microbiology: Body Systems Edition. Jones & Bartlett Publishers. p. 768. ISBN 9781449605940.
  10. Copstead-Kirkhorn, Lee-Ellen C.; Banasik, Jacquelyn L. (2014-06-25). Pathophysiology. Elsevier Health Sciences. p. 395. ISBN 9780323293174.
  11. Kahan, Scott (2008-03-01). Signs and Symptoms. Lippincott Williams & Wilkins. p. 234. ISBN 9780781770439.
  12. Diepenbrock, Nancy H. (2011-02-15). Quick Reference to Critical Care. Lippincott Williams & Wilkins. p. 391. ISBN 9781608314645.
  13. Clubbing of the Nails~clinical at eMedicine
  14. Loewe, Leo (1944). "Combined penicillin and heparin therapy of subacute bacterial endocarditis". Journal of the American Medical Association. 124 (3): 270–272. doi:10.1001/jama.1944.02850030012003. PMC 1871521. PMID 19312479.

Further references
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