Infective endocarditis

Michael D Morris MD (Dr. Morris of University of Florida, Gainesville, has no relevant financial relationships to disclose.)
Katharina M Busl MD MS (Dr. Busl of University of Florida, Gainesville, has no relevant financial relationships to disclose.)
John E Greenlee MD, editor. (

Dr. Greenlee of the University of Utah School of Medicine has no relevant financial relationships to disclose.

Originally released October 30, 1995; last updated November 28, 2018; expires November 28, 2021

This article includes discussion of infective endocarditis, SBE, native valve endocarditis, prosthetic valve endocarditis, culture-negative infective endocarditis, and fungal endocarditis. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


An estimated 15,000 to 20,000 new cases of infective endocarditis are diagnosed annually in the United States. Neurologic complications can be the initial or predominant manifestation of the disease, and they have become a leading cause of disease mortality. Staphylococcus aureus is the leading causative organism, and intravenous drug abuse is disproportionately represented as a risk factor in patients with neurologic complications. Symptomatic cerebral complications occur in up to 55% of patients with infective endocarditis, often before the diagnosis of infective endocarditis is made, and the complications include stroke, intracranial hemorrhage, brain abscess, mycotic aneurysms, and meningoencephalitis. Rapid diagnosis and initiation of antimicrobial therapy is still be the most effective means to prevent neurologic complications. Endovascular embolization or coiling of aneurysms or parent arteries can be used to treat selected cases of cerebral mycotic aneurysms. Endovascular thrombectomy is used in select cases of embolic ischemic stroke. Antiplatelet therapy remains controversial for secondary stroke prevention or continuation in patients that were on antiplatelets prior to development of infective endocarditis, but it is considered necessary after stent placement to prevent rethrombosis. Although traditionally postponed, early valve surgery has gained traction in recent years with cumulative evidence of potential mortality benefit in select cases.

Key points


Staphylococcus aureus is the leading causative organism for infective endocarditis.


• Among neurologic complications, cerebral embolism and its consequences still remain the most common.


• Antibiotic prophylaxis for at-risk individuals before dental or other such interventions remains questionable.


• Rapid diagnosis and early antibiotic intervention still remain the mainstays to avoid neurologic complications.


• The National Institute for Health and Clinical Excellence guidance questions the role of antibiotic prophylaxis in individuals at risk for endocarditis prior to interventions.

Historical note and terminology

Infective endocarditis reflects both the rich tradition of bedside clinical diagnosis and the evolving technical developments in neuroimaging and cardiac surgery. Its manifestations have been documented by clinicians over the last several centuries, including thorough discussions of the CNS complications associated with the disease. Although infective endocarditis was probably recognized as a specific entity in 1646 by Riviere, its manifestations were described fully during the 19th century (Major 1945). Virchow, in 1846, was the first to recognize the occurrence of embolic events during infective endocarditis (Major 1945). A little-known English doctor, William Senhouse Kirkes (1822-1864), gave the first account of embolism from vegetations in infective endocarditis in 1852 (Cameron 2000). Sir William Osler s 3 Goulstonian lectures in 1885 at the Royal College of Physicians in London served to document his extraordinary experience with the full clinical spectrum of “malignant endocarditis” (Osler 1885). Osler had a particular interest in the pathophysiology of distant complications associated with endocarditis, including those involving the CNS: “The meningeal complications of endocarditis have not received much attention, considering the frequency with which it has occurred...somewhat over 12%. In the majority of these cases it occurred in connexion with pneumonia” (Osler 1885). His diagnostic principles are still valid today: “With careful blood-cultures one should now be able to determine the presence of septicemia....The blood-culture and the presence of the painful erythematous nodules and the occurrence of embolism furnish the most important aids (to diagnosis)” (Osler 1909). Thayer proposed the term “infective” endocarditis to replace the older term of “bacterial” endocarditis, as it became clear that a wide range of pathogens including bacteria, rickettsiae, and fungi could be responsible for the disease (Thayer 1931).

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