Health Encyclopedia

Culture-negative endocarditis

Definition

Culture-negative endocarditis in an infection and inflammation of the lining of one or more heart valves in which no endocarditis-causing germs can be identified on a blood culture. The reason for this is that certain germs just do not grow well in the laboratory setting, or because some patients have previously received antibiotics that keep such germs from growing.

Alternative Names

Endocarditis (culture-negative)

Causes, incidence, and risk factors

Endocarditis is usually a result of a blood infection. Bacteria can enter the bloodstream during certain medical procedures, including dental procedures, and travel to the heart, where it can settle on damaged heart valves.

Existing heart disease and problems with your heart valves make you more likely to develop endocarditis. Risk factors include:

Artificial heart valves
Congenital heart disease (atrial septal defect, patent ductus arteriosus, and others)
Heart valve problems (such as mitral insufficiency)
History of rheumatic heart disease or previous endocarditis

Intravenous drug users are also at risk for this condition, because dirty needles can cause bacteria to enter the bloodstream.

However, an organism commonly found in the mouth, Streptococcus viridans, can cause endocarditis. This is why dental procedures increase your chances for developing this condition. Such procedures are especially risk for children with congenital heart conditions. As a result, it is common practice for children with some forms of congenital heart disease and adults with certain heart-valve conditions to take antibiotics before any dental work.

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

Symptoms

Symptoms of endocarditis may develop slowly (subacute) or suddenly (acute). Fever is the classic symptom and may persist for days before any other symptoms appear.

Other symptoms may include extreme fatigue and breathing difficulty.

Signs and tests

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.

A physical exam may reveal:

Heart murmur
Tachycardia (fast heart rate)

The following tests may be done:

Chest x-ray
Complete blood count
Echocardiogram (ultrasound of the heart)
EKG
Transesophageal echocardiogram (TEE), a special echocardiogram done by introducing a small probe into the patient's mouth and down the esophagus

Treatment

You will be admitted to the hospital so you can receive medicines through a vein. Long-term, high-dose antibiotic or antifungal treatment is needed. Treatment is usually given for 4-6 weeks.

Surgery may be needed to replace damage heart valves.

Expectations (prognosis)

Heart valves may be damaged if diagnosis and treatment are delayed.

Complications

Abnormal connections within the heart
Blood clots that travel to brain, kidneys, lungs, or abdomen
Brain abscess
Congestive heart failure
Rapid or irregular heartbeats, including atrial fibrillation
Severe valve damage
Stroke

Prevention

Preventive antibiotics are often given to people at risk for infectious endocarditis before dental procedures or surgeries involving the respiratory, urinary, or intestinal tract. The American Heart Association antibiotics before a dental procedure if you have:

Artificial heart valves
Certain congenital heart defects, both before or possibly after repair
History of infective endocarditis
Valve problems after a heart transplant

Continued medical follow-up is recommended for people with a previous history of infectious endocarditis.

Persons who use intravenous drugs should seek treatment for addiction. If this is not possible, use a new needle for each injection, avoiding sharing any injection-related paraphernalia, and use alcohol pads before injecting to reduce risk.

References

Mandell GL, Bennett JE, Dolin R. Principles and Practice of Infectious Diseases. 6th ed. London: Churchill Livingstone; 2005; pp 975-1022.

Karchmer AW. Infective Endocarditis. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. St. Louis, Mo: WB Saunders; 2007: chap 63.

Review Date:4/25/2008
Reviewed By:Mark Levin, MD, Division of Infectious Disease, MacNeal Hospital, Berwyn, IL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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