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Culture-negative endocarditis

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Definition:

Endocarditis is infection and inflammation of the lining of a valve in the heart.

Culture-negative endocarditis is a type of endocarditis in which no endocarditis-causing organisms can be grown in a culture taken from a blood sample. This sometimes occurs when blood cultures are drawn after antibiotic treatment already started, or if the organism is difficult to grow in a culture.

Alternative Names:

Endocarditis (culture-negative)

Causes, incidence, and risk factors:

Endocarditis is most likely to occur in people whose cardiac valves are vulnerable to infection. For example, the valves may have been scarred in childhood by rheumatic fever, or are abnormal from birth (bicuspid aortic valve or mitral valve prolapse). Persons with prosthetic valves (valves which have been surgically replaced) are also more prone to having bacteria collect and grow prosthetic "vegetations."

Other patients at increased risk for endocarditis are those with previous endocarditis or congenital heart diseases. Intravenous drug users are also at especially high risk of acquiring culture-negative endocarditis from contaminated syringes.

In patients with endocarditis there is usually an obvious source of infection, such as an infected catheter, a dental abscess, or an infected skin lesion. However, in many patients there is no history of infection.

An estimated 10,000 to 15,000 new cases of endocarditis are diagnosed yearly in the United States.

• Review Date: 5/26/2006
• Reviewed By: Monica Gandhi MD, MPH, Assistant Professor, Division of Infectious Diseases, UCSF, San Francisco, CA. Review provided by VeriMed Healthcare Network.

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