Bacterial infective endocarditis
Bacterial infection of the endocardial surface, usually a heart valve, producing vegetations that destroy the valve and embolize; diagnosis rests on the modified Duke criteria (blood cultures plus echocardiography) and treatment is a prolonged organism-directed intravenous antibiotic course, with valve surgery for heart failure, uncontrolled infection, or embolic recurrence.
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What this article covers
- Overview
Infection of the endocardial surface, almost always a heart valve: bacteria colonize a valve (native or prosthetic), forming a vegetation of platelets, fibrin, and organisms that destroys the valve locally and sheds emboli systemically.
- Epidemiology
Predisposing valvular lesions in the absence of prosthetic material: mitral valve prolapse, bicuspid aortic valve, and aortic sclerosis are the principal underlying lesions for native valve IE.
- Risk factors
Prosthetic heart valve: the single highest-risk lesion for IE and for the highest mortality if infected.
- Pathophysiology
Endothelial injury or turbulent flow initiates a sterile platelet-fibrin thrombus at sites of high-velocity jets or structural abnormality.
- Clinical features
Fever plus a new or changing murmur is the cardinal presentation and should trigger blood cultures and echocardiography; a worsening or changing preexisting murmur alone does not meet the Duke definition of new valvular regurgitation.
- Differential diagnosis
Acute rheumatic fever: acute rheumatic fever causes valvulitis and murmur after streptococcal pharyngitis, but presents with migratory polyarthritis, carditis, chorea, and erythema marginatum rather…
- Diagnosis
The diagnosis is established using the modified Duke criteria: definite IE requires 2 major criteria, or 1 major plus 3 minor criteria, or 5 minor criteria; possible IE requires 1 major plus 1 minor, or 3 minor criteria.
- Management
First, obtain blood cultures, then start empiric intravenous antibiotics chosen by clinical acuity and suspected organism while cultures are pending; do not delay therapy in a hemodynamically unstable or rapidly deteriorating patient.
- Complications
Heart failure from valve destruction is the most common cause of death in IE and the leading indication for surgery.
- Prognosis
Persistent bacteremia, heart failure, abscess, and stroke predict higher mortality in prosthetic valve IE, which is worse than native valve IE.
- Prevention
Antibiotic prophylaxis before dental procedures involving gingival manipulation or oral mucosal perforation is recommended only for high-risk cardiac conditions: prosthetic valve/valve-repair…
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