Endocarditis classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Maliha Shakil, M.D. [2]
Overview
Endocarditis may be classified based on the underlying pathophysiology of the process (infective vs. non-infective), the onset of the disease (acute vs. subacute or short incubation vs. long incubation), results of the cultures (culture positive vs. culture negative), the nature of the valve (native vs. prosthetic) and the valve affected (aortic, mitral, or tricuspid valve).
Classification
endocarditis may be classified into 4 subtypes based on:
- Infective Endocarditis vs. Non-Infective Endocarditis
- Infectious endocarditis is due to bacterial infection but other organisms may also be responsible.
- Endothelium valve damage improves the ability of bacteria to bind to the valve surface.
- Non-infective or marantic endocarditis is a rare condition.
- Libman-Sacks endocarditis is a form of sterile endocarditis, which mostly happens in systemic lupus erythematosus and antiphospholipid syndrome patients.
- Non-infective endocarditis may also occur in patients with cancer, particularly mucinous adenocarcinoma in the setting of Trousseau syndrome.
- Short Incubation vs. Long Incubation
- Traditionally, infective endocarditis has been clinically divided into acute and subacute endocarditis. This classifies both the rate of progression and severity of disease.
- Subacute bacterial endocarditis (SBE) is often due to streptococci of low virulence and is a mild to moderate illness which progresses slowly over weeks and months.
- Acute bacterial endocarditis (ABE) is a fulminant illness that progresses rapidly over days to weeks and is more likely to be due to Staphylococcus aureus, which has much greater virulence.
- The terms short incubation (<6 weeks) and long incubation (>6 weeks) are preferred.
- Culture Positive vs. Culture Negative
- Infective endocarditis may also be classified as culture-positive or culture-negative.
- Culture-negative endocarditis is due to micro-organisms that require a longer period of time to be identified in the laboratory. Such organisms are said to be fastidious because they have demanding growth requirements.
- Some pathogens responsible for culture-negative endocarditis include Aspergillus species, Brucella species, Coxiella burnetii, Chlamydia species, and HACEK bacteria.
- Native Valve Endocarditis vs. Prosthetic Valve Endocarditis
- The distinction between native-valve endocarditis and prosthetic-valve endocarditis is clinically important.
- Prosthetic-valve endocarditis constitutes 10-20% of cases of endocarditis.
- The greatest risk is during the first 6 months after valve surgery.
- Staphylococcus epidermidis is the most common cause of prosthetic-valve endocarditis.