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Infective Endocarditis

Practice Essentials

Infective endocarditis (IE) is defined as an infection of the endocardial surfaces of the heart—primarily of 1 or more heart valves, the mural endocardium, or a septal defect. Its intracardiac effects include severe valvular insufficiency, intractable congestive heart failure, and myocardial abscesses. If left untreated, IE is inevitably fatal.

Acute bacterial endocarditis caused by Staphylococ

Acute bacterial endocarditis caused by Staphylococcus aureus with perforation of the aortic valve and aortic valve vegetations. Courtesy of Janet Jones, MD, Laboratory Service, Wichita Veterans Affairs Medical Center.

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Signs and symptoms

Fever, often low-grade and intermittent, is present in up to 90% of patients with IE. Heart murmurs are heard in approximately 85% of patients.

As many as 50% of patients may have 1 or more classic signs of subacute IE. As a result of their immunologic derivation, these signs are almost exclusively seen in subacute disease and may be underappreciated because of their subtle nature. Signs and symptoms include the following
:

Petechiae 

Subungual (splinter) hemorrhages: Dark red, linear lesions in the nail beds

Osler nodes: Tender subcutaneous nodules usually found on the distal pads of the digits

Janeway lesions: Nontender maculae on the palms and soles

Roth spots: Retinal hemorrhages with small, clear centers (rare)

Signs of neurologic disease, which occur in as many as 40% of patients, include the following
:

Embolic stroke with focal neurologic deficits (the most common neurologic sign)

Intracerebral hemorrhage

Multiple microabscesses

Other signs of IE include the following:

Splenomegaly

Stiff neck

Delirium

Paralysis, hemiparesis, aphasia

Conjunctival hemorrhage

Pallor

Gallops

Rales

Cardiac arrhythmia

Pericardial rub

Pleural friction rub

Subacute native valve endocarditis

The symptoms of early subacute native valve endocarditis (NVE) are usually subtle and nonspecific; they include the following:

Low-grade fever (absent in 3-15% of patients)

Anorexia

Weight loss

Influenzalike syndromes

Polymyalgia-like syndromes

Pleuritic pain

Syndromes similar to rheumatic fever, such as fever, dulled sensorium (as in typhoid), headaches

Abdominal symptoms, such as right upper quadrant pain, vomiting, postprandial distress, appendicitis-like symptoms

Diagnosis

The Duke diagnostic criteria, developed by Durack and colleagues, are generally used to make a definitive diagnosis of IE. The criteria combine the clinical, microbiologic, pathologic, and echocardiographic characteristics of a specific case
:

Major blood culture criteria for IE include the following:

Two blood cultures positive for organisms typically found in patients with IE

Blood cultures persistently positive for 1 of these organisms, from cultures drawn more than 12 hours apart

Three or more separate blood cultures drawn at least 1 hour apart

Major echocardiographic criteria include the following:

Echocardiogram positive for IE, documented by an oscillating intracardiac mass on a valve or on supporting structures, in the path of regurgitant jets, or on implanted material, in the absence of an alternative anatomic explanation

Myocardial abscess

Development of partial dehiscence of a prosthetic valve

New-onset valvular regurgitation

Minor criteria for IE include the following:

Predisposing heart condition or intravenous drug use (IVDA)

Fever of 38°C (100.4°F) or higher

Vascular phenomenon, including major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhage, or Janeway lesions

Immunologic phenomenon such as glomerulonephritis, Osler nodes, Roth spots, or rheumatoid factor

Positive blood culture results not meeting major criteria or serologic evidence of active infection with an organism consistent with IE

Echocardiogram results consistent with IE but not meeting major echocardiographic criteria

A definitive clinical diagnosis can be made on the basis of the following:

Two major criteria

One major criterion and 3 minor criteria

Five minor criteria

Management

Antibiotics remain the mainstay of treatment for IE. Three to 5 sets of blood cultures should be obtained within 60 to 90 minutes, followed by the infusion of the appropriate antibiotic regimen. By necessity, the initial antibiotic choice is empiric in nature, determined by clinical history and physical examination findings.

Empiric antibiotic therapy is chosen on the basis of the most likely infecting organisms. Native valve endocarditis (NVE) has often been treated with penicillin G and gentamicin for synergistic coverage of streptococci. Patients with a history of intravenous drug abuse (IVDA) have been treated with nafcillin and gentamicin to cover for methicillin-sensitive staphylococci. The emergence of methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-resistant streptococci has led to a change in empiric treatment, with liberal substitution of vancomycin in place of a penicillin antibiotic.

 

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