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Infective Endocarditis

Written by Ada’s Medical Knowledge Team

Updated on

What is infective endocarditis?

Infective endocarditis is an infection of the inner lining of the heart and the heart valves, called the endocardium. The infection is caused by certain bacteria or, less often, fungi entering the bloodstream.

Infective endocarditis usually affects people who have a damaged heart, who:

  • Have an artificial device in their heart
  • Have a congenital heart defect
  • Have had endocarditis before
  • Inject drugs intravenously

It is an uncommon condition, with around 15,000 new cases in the United States each year. 1

Symptoms vary from person to person, but can include fever, shortness of breath and skin changes. Treatment is with intravenous antibiotics, initially administered in hospital. Surgery may be necessary to repair any damage to the heart. Without treatment, infective endocarditis can be life-threatening. 2 3

Symptoms of infective endocarditis

Symptoms of infective endocarditis vary depending on the type of bacterium or fungus causing the infection and the overall health of the person. Symptoms can appear suddenly, which is called acute infective endocarditis, or gradually over several months; this is called subacute infective endocarditis. 1 2

Common symptoms of infective endocarditis include: 1 2

  • Fever
  • Chills
  • Sweating at night
  • Heart murmur or change in heart murmur, i.e. an abnormal sound made by the heart between beats
  • Nausea and vomiting
  • Feeling tired
  • Aching muscles and joints
  • Chest and/or back pain
  • Malaise and fatigue
  • Weakness
  • Headache
  • Lack of appetite
  • Weight loss
  • Small, painful, red or purple bumps on the fingers and/or toes, called Osler nodes
  • Very small, painless, dark spots on the palms of the hands and/or soles of the feet, called Janeway lesions
  • Small spots, caused by broken blood vessels, under fingernails, called splinter hemorrhages or on chest, whites of eyes or in mouth
  • Swelling in the feet or legs

If you are concerned that you or someone you know may have infective endocarditis, you can do a free Ada symptom assessment at any time.

Complications of infective endocarditis

Infective endocarditis can cause other conditions, some of which are very serious. They are generally caused by emboli, which are small pieces of matter that break away from the infection site and travel to other parts of the body where they can cause abscesses, which are painful collections of pus, and other problems. 2

Further heart problems

Up to 50 percent of people with infective endocarditis develop further heart problems. These can include: 1 2 4 5

  • Heart murmur
  • Congestive heart failure
  • Arrhythmia, which is an abnormality of the rhythm of the heart beat
  • Damage to heart valves, which may manifest as a heart murmur, an abnormal sound made by the heart between beats
  • An abscess, a collection of pus in the heart tissue
  • Heart attack

Some of the conditions listed above can occur immediately, but others may develop and become apparent only some time later.

Pulmonary embolism

A pulmonary embolism occurs when a blood clot blocks blood flow to the lungs. In infective endocarditis, the cause of the clot is an emboli. Pulmonary embolism is an extremely serious condition and can be life-threatening if not treated quickly. Symptoms include: 6

  • Shortness of breath
  • Chest pain
  • Persistent cough
  • Dizziness

For more information, see the resource on pulmonary embolism.

Strokes and seizures

Up to 40 percent of people with infective endocarditis will experience some form of neurological complication. Stroke is the most common neurological complication to experience. 7

If emboli reach the brain, they can cause a stroke or seizure. Both conditions are very serious and can be life-threatening. Symptoms of a stroke include:

  • Weakness or drooping in the face, often on one side only
  • Numbness, weakness or pins and needles in one or both arms
  • Difficulty speaking or slurred speech

For more information, see the resource on ischemic stroke.

Complications involving organs other than the heart

Some cases of complications of infective endocarditis are caused by clumps of cells and other matter which form in the bloodstream around the infection site. These clumps of matter are called vegetations. Parts of a vegetation, called emboli, can break off and travel via the bloodstream to other parts of the body, causing complications such as abscesses or seizures.

Conditions that may develop in the brain from emboli caused by infective endocarditis include: 2 7

Problems relating to the lungs can include pneumonia or a buildup of fluid around the lungs. If an emboli becomes septic, it can cause pus to build up around the lungs. 2 8

Infective endocarditis can cause glomerulonephritis, which is a condition where the kidneys become inflamed and stop filtering metabolic waste products properly. Symptoms include a puffy face, flank pain, urinating less than usual and blood in the urine. If left untreated, glomerulonephritis can lead to kidney failure. 8 9

The spleen may also become enlarged, a condition called splenomegaly, which can cause abdominal pain and a feeling of fullness when eating. 10

Causes of infective endocarditis

Infective endocarditis is caused by bacteria or fungi entering the bloodstream and settling on the endocardium, which is the inner lining of the heart and heart valves. The most common types of organism responsible for infective endocarditis are: 8 11 12 13 14 15

  • Staphylococcus aureus, which is the most common cause of infective endocarditis
  • Streptococci, which is the second most common cause of infective endocarditis
  • Pseudomonas aeruginosa, most often found in hospital-acquired infections
  • Enterococci, most often found in elderly men and acquired via the genitourinary tract
  • A fungus, such as Aspergillus

These infections can be acquired in various ways, such as: 2 7 16

  • Intravenous drug use
  • When a medical device is inserted into a vein, such as an intravenous catheter, a device for inserting medication or other liquids directly into a vein, or a pacing wire, a temporary device to stabilize a slow heartbeat
  • Dental hygiene and dental procedures if the teeth and gums are in poor condition
  • Infections in other body parts, such as the gut, genitourinary tract or skin

Good to know: Most people with infective endocarditis also have a heart defect or a prosthetic device in the heart, such as an artificial heart valve or a pacemaker. Damaged and artificial sites in the heart encourage blood clotting and the formation of structures called thrombi, which provide bacteria with a place to thrive. Some bacteria, such as Staphylococcus aureus are able to infect people who have healthy hearts, but this is uncommon. 1 17 18

Diagnosis of infective endocarditis

Diagnosis of infective endocarditis is based on the symptoms described, physical examination and certain diagnostic tests. Diagnosis can be difficult because subacute infective endocarditis can develop gradually over many months, and because, in the modern era, few people present with classical symptoms of fever, heart murmur, bacteremia 19, Osler nodes or Janeway’s lesions. 8 20

Infective endocarditis should be suspected if the affected person has a fever and also:

  • Has used intravenous drugs
  • Has a cardiac device such as a pacemaker or a prosthetic valve
  • Has a congenital heart disease
  • Has recently had a dental procedure
  • Has recently had an infection

To identify the type of organism causing the endocarditis, three or more sets of blood cultures will be drawn from different sites on the body, over 24 hours. However, if the person has previously been given antibiotics, the cultures may be negative. One study found negative blood cultures in many of the people examined. 20 If you’re concerned about infective endocarditis, you can do a free symptom assessment for yourself or someone else by using the Ada app.

Imaging studies can reveal signs of heart damage or vegetation. Tests normally performed include: 1 8 21

  • Echocardiography, which uses ultrasound waves to produce an image of the heart and heart valves
  • Computerized tomography (CT) scan and an MRI scan, which can detect complications of infective endocarditis

Treatment of infective endocarditis

Treating infective endocarditis is done by administering intravenous antibiotics normally for between two to eight weeks. The type of antibiotic will depend on the cause of the infection and whether there is antibiotic resistance. Treatment is usually begun in hospital to allow the person to be monitored by a cardiologist and infectious disease specialist for signs of improvement. 2 8

Surgery may be needed to repair damage to heart valves or to remove sources of bacteremia 19. If infective endocarditis is caused by a fungus, the person will likely need to undergo surgery, as this form of the condition is more difficult to treat. 2

Preventing infective endocarditis

Some people are more at risk of infective endocarditis than others. These include people who:

  • Have an existing heart defect or a congenital heart defect
  • Have an artificial device implanted in the heart
  • Use intravenous drugs
  • Have had endocarditis before

These people should be aware of the symptoms of infective endocarditis and see a doctor immediately if they suspect infection. Anyone at high risk should practice good hygiene, which includes: 2 8

  • Taking care of teeth and gums, including gentle flossing and using a soft toothbrush that does not abrade the gums, as infection can enter the body via a gum infection
  • Keeping dentists informed of the risk of infective endocarditis, as they may decide to prescribe a course of antibiotics before any procedure
  • Practicing sterile needle use when injecting into the veins
  • Avoiding tattoos and body piercings
  • Taking care with any catheter or other device inserted into a vein, particularly during any stay in hospital

Infective endocarditis FAQs

Q: Is infective endocarditis deadly?
A: Without treatment, infective endocarditis is generally fatal. However, with early detection and treatment the prognosis is often good.

Other names for infective endocarditis

  • Bacterial endocarditis
  • Heart valve infection
  • Infectious endocarditis
  • Fungal endocarditis