Infectious endocarditis

Alternative names
Endocarditis - infectious


Infectious endocarditis is an infection of the lining of the heart chambers and heart valves caused by bacteria, viruses, fungi, or other infectious agents.

Causes, incidence, and risk factors

Infectious endocarditis is an inflammation of the heart valves. It can affect the heart muscle (myocarditis) or the lining of the heart (pericarditis). Most people who develop infectious endocarditis have underlying heart disease.

The infection may be bacteremia (bacteria in the blood), which is common during dental, upper respiratory, urologic, and lower gastrointestinal diagnostic and surgical procedures. The infection can cause growths on the heart valves, the lining of the heart, or the lining of the blood vessels. These growths may form clots that break off and travel to the brain, lungs, kidneys, or spleen.

Many bacteria can cause endocarditis, but an organism commonly found in the mouth, Streptococcus viridans, is responsible for approximately half of all bacterial endocarditis. Other common organisms include staphylococcus and enterococcus. Less common organisms include pseudomonas, serratia, candida, and many others.

Symptoms of endocarditis may develop slowly (subacute) or suddenly (acute). Fever is a hallmark of both. In the slower form, fever may be present on a daily basis for months before other symptoms appear. Other symptoms are nonspecific, such as fatigue, malaise (general discomfort), headache, and night sweats. As the illness progresses, small dark lines, called splinter hemorrhages, may appear under the fingernails.

The health care provider may hear changing murmurs in the heart and detect an enlarged spleen and mild anemia. Murmurs result from changes in blood flow across valves when clumps of bacteria, fibrin and cellular debris, called vegetations, collect on the heart valves. The mitral valve is most commonly affected, followed by the aortic valve.

Preexisting conditions that increase the likelihood of developing endocarditis include:

  • Congenital heart disease (atrial septal defect, patent ductus arteriosus, and others)  
  • Prior rheumatic heart disease  
  • Cardiac valve anomalies (such as mitral insufficiency)  
  • Artificial heart valves

Since Streptococcus viridans is often found in the mouth, dental procedures are the most common cause of bacterial endocarditis. This can put children with congenital heart conditions at risk. As a result, it is common practice for children with some forms of congenital heart disease to start on antibiotics prior to any dental work.


  • Fatigue  
  • Weakness  
  • Fever  
  • Chills  
  • Night sweats (may be severe)  
  • Weight loss  
  • Muscle aches and pains  
  • Heart murmur  
  • Shortness of breath with activity  
  • Swelling of feet, legs, abdomen  
  • Blood in the urine  
  • Excessive sweating  
  • Red skin spots on the palms and soles (Janeway lesions)  
  • Paleness  
  • Nail abnormalities (splinter hemorrhages under the nails)  
  • Joint pain  
  • Abnormal urine color  
  • Red, painful intradermal nodes in the pads of the fingers and toes called Osler’s nodes

Signs and tests

A history of congenital heart disease raises the level of suspicion. A physical examination may show an enlarged spleen. The examiner may detect a new heart murmur, or a change in a previous heart murmur. Examination of the nails may show splinter hemorrhages. Eye examination may show retinal hemorrhages with a central area of clearing, called Roth’s spots.

The following tests that may be performed:

  • Repeated blood culture and sensitivity (#1 test for detection)  
  • ESR (erythrocyte sedimentation rate)  
  • CBC (complete blood count) may show low grade, microcytic (small red blood cells) anemia  
  • Echocardiogram  
  • Transesophageal echocardiogram  
  • Chest x-ray  
  • CT scan of the chest  
  • ASO (anti-streptolysin O) test


Hospitalization is required initially to administer intravenous antibiotics. Long-term, high-dose antibiotic therapy is required to eradicate the bacteria from the heart chambers and vegetations on the valves. Therapy up to 6 weeks is not uncommon. The chosen antibiotic must be specific for the organism causing the condition. This is determined by the blood culture and the sensitivities tests.

If heart failure develops as a result of damaged heart valves, surgery to replace the affected heart valve may be indicated.

Expectations (prognosis)
Early treatment of bacterial endocarditis generally has a good outcome. Heart valves may be damaged if diagnosis and treatment is delayed.


  • Congestive heart failure if treatment is delayed  
  • Blood clots or emboli that travel to brain, kidneys, lungs, or abdomen, causing severe damage  
  • Arrhythmias (rapid or irregular heartbeat), such as atrial fibrillation  
  • Glomerulonephritis  
  • Severe valve damage  
  • Stroke  
  • Brain abscess  
  • Neurologic changes  
  • Jaundice

Calling your health care provider

Call your health care provider if you note the following symptoms during or after treatment:

  • Weight loss without change in diet  
  • Blood in urine  
  • Chest pain  
  • Weakness  
  • Numbness or weakness of muscles  
  • Fever


Preventive antibiotics are often given to people with predisposing congenital or valvular abnormalities before dental procedures or surgeries involving the respiratory, urinary or intestinal tract. Continued medical follow-up is advised for people with a previous history of infective endocarditis.

Intravenous drug users are also at risk for this condition because unsterile injecting practices increase the exposure of the bloodstream to infectious agents. Treatment for addiction should be sought. If this is not possible, use of a new needle for each injection, avoiding sharing any injection-related paraphernalia and use of alcohol pads to sterilize the injection site can reduce risk.

Johns Hopkins patient information

Last revised: December 3, 2012
by Martin A. Harms, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.