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Infective endocarditis: general information
Medical expert of the article
Last reviewed: 12.07.2025
Infective endocarditis is an infectious lesion of the endocardium, usually bacterial (usually streptococcal and staphylococcal) or fungal. It causes fever, heart murmurs, petechiae, anemia, embolic episodes, and endocardial vegetations. Vegetations may lead to valvular insufficiency or obstruction, myocardial abscess, or mycotic aneurysm. Diagnosis requires detection of microorganisms in the blood and (usually) echocardiography. Treatment of infective endocarditis consists of long-term antimicrobial therapy and (sometimes) surgical methods.
Endocarditis can develop at any age. Men are affected twice as often. People with immunodeficiency and drug addicts who inject drugs intravenously are the highest risk group.
[ What causes infective endocarditis?
Normally, the heart is relatively resistant to infections. Bacteria and fungi have difficulty attaching to the endocardial surface because the constant blood flow prevents this. Two factors are necessary for the development of endocarditis: predisposing changes in the endocardium and the presence of microorganisms in the blood (bacteremia). Sometimes massive bacteremia and/or particularly pathogenic microorganisms cause endocarditis of intact valves.
Symptoms of infective endocarditis
Initially, symptoms are vague: low-grade fever (< 39 °C), night sweats, fatigue, malaise, and weight loss. Cold-like symptoms and arthralgia may occur. Manifestations of valvular insufficiency may be the first finding. Up to 15% of patients initially have fever or a murmur, but eventually almost all develop both. Physical examination findings may be normal or include pallor, fever, changes in a preexisting murmur, or development of a new regurgitant murmur and tachycardia.
Where does it hurt?
Diagnosis of infective endocarditis
Because symptoms are nonspecific, highly variable, and may develop insidiously, a high index of suspicion is required. Endocarditis should be suspected in febrile patients without obvious sources of infection, particularly if a heart murmur is present. Suspicion for endocarditis should be high if blood cultures are positive in a patient with a history of valvular disease, recent invasive procedures, or intravenous drug use. Patients with documented bacteremia should undergo repeated, complete evaluations for new valvular murmurs and signs of embolism.
What do need to examine?
How to examine?
Who to contact?
Treatment of infective endocarditis
Treatment consists of a long course of antimicrobial therapy. Surgery may be necessary for complications that disrupt the biomechanics of the valve apparatus or resistant microorganisms. Antibiotics are usually administered intravenously. Since the duration of therapy is 2-8 weeks, intravenous injections are often performed on an outpatient basis.
Any sources of bacteremia should be aggressively addressed, including surgical excision of necrotic tissue, drainage of abscesses, and removal of foreign material and infected devices. Intravenous catheters (especially central venous) should be replaced. If endocarditis develops in a patient with a newly inserted central venous catheter, it should be removed. Organisms present on catheters and other devices are unlikely to respond to antimicrobial therapy, leading to treatment failure or relapse. If continuous infusions are used instead of intermittent bolus administration, the interval between infusions should not be too long.
Prognosis of infective endocarditis
Without treatment, infective endocarditis is always fatal. Even with treatment, death is likely, and the prognosis is generally poor for the elderly and those with resistant organisms, previous illnesses, or prolonged untreated disease. The prognosis is also worse in patients with aortic valve or multiple valve involvement, large vegetations, polymicrobial bacteremia, infection of the prosthetic valve, mycotic aneurysms, valve ring abscesses, and massive emboli. Mortality in streptococcal endocarditis without major complications is less than 10%, but is virtually 100% in aspergillosis endocarditis following surgical valve replacement.
The prognosis is better with right-sided than with left-sided endocarditis because tricuspid valve dysfunction is better tolerated, systemic emboli are absent, and right-sided endocarditis caused by Staphylococcus aureus responds better to antimicrobial therapy.