Infective endocarditis: organism sources and important associations
THE CONTEXT
The organisms causing endocarditis differ in their routes of bloodstream entry, clinical behaviour and associated conditions.
Oral, bowel and urinary sources
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Oral viridans streptococci can enter the bloodstream during dental treatment and are common causes of subacute endocarditis.
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Enterococcus faecalis, Enterococcus faecium and Streptococcus gallolyticus subsp. gallolyticus may enter the bloodstream from the bowel or urinary tract.
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Streptococcus gallolyticus subsp. gallolyticus was previously known as Streptococcus bovis.
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Patients with Streptococcus gallolyticus endocarditis should undergo colonoscopy because of its association with large-bowel malignancy.
Acute endocarditis
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Staphylococcus aureus has overtaken streptococci as the most common cause of acute endocarditis.
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Sources include skin infections, abscesses, intravenous or central vascular access sites, and intravenous drug use.
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Staphylococcus aureus is highly virulent and invasive, usually causing florid vegetations, rapid valve destruction and abscess formation.
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Other causes of acute endocarditis include Streptococcus pneumoniae and Streptococcus pyogenes.