What Is It?

Endocarditis, also called infective endocarditis, is an infection and inflammation of the heart valves and endocardium (the inner lining of the heart chambers). Endocarditis occurs when infectious organisms, such as bacteria or fungi, enter the bloodstream and settle inside the heart. In most cases, these organisms are streptococci (“strep”), staphylococci (“staph”) or species of bacteria that normally live on body surfaces. The infecting organism enters the bloodstream through a break in the skin caused by a skin disorder or injury, a medical or dental procedure, or a skin prick, especially among intravenous drug users.

Depending on the aggressiveness (virulence) of the infecting germ, the heart damage caused by endocarditis may be swift and severe (acute endocarditis) or slower and less dramatic (subacute endocarditis). There are other important distinctions between acute and subacute endocarditis:

  • Acute endocarditis — Acute endocarditis most often occurs when an aggressive species of skin bacteria, especially a staphylococcus, enters the bloodstream and attacks a normal, undamaged heart valve. Once staph bacteria begin to multiply inside the heart, they may send small clumps of bacteria called septic emboli into the bloodstream to spread the infection to other organs, especially to the kidneys, lungs and brain. Intravenous (IV) drug users are at very high risk for acute endocarditis, since their addiction allows aggressive staph bacteria many opportunities to enter the blood through broken skin. Dirty drug paraphernalia increases the risk. If untreated, this form of endocarditis can be fatal in less than six weeks.
  • Subacute endocarditis — This form of endocarditis most often is caused by one of the viridans group of streptococci (Streptococcus sanguis, mutans, mitis, or milleri) that normally live in the mouth and throat. Streptococcus bovis or Streptococcus equinus also can cause subacute endocarditis, typically in patients who have some form of gastrointestinal cancer, usually colon cancer. Subacute endocarditis tends to involve heart valves that already are damaged in some way, and it usually is less likely to cause septic emboli than acute endocarditis. If untreated, subacute bacterial endocarditis can progress for as long as one year before it is fatal.

Endocarditis strikes approximately 19,000 people in the United States annually, with 2,000 deaths. Men develop endocarditis more often than women, and the illness is more common among people of either sex who have one or more of the following risk factors:

  • A congenital (present at birth) malformation of the heart or a heart valve, or mitral-valve prolapse with mitral-valve regurgitation
  • A heart valve damaged by rheumatic fever or by age-related valve thickening with calcium deposits
  • An implanted device in the heart ( pacemaker wire, artificial heart valve )
  • A history of IV drug use
  • A chronic medical condition that weakens the immune system (alcoholism, diabetes, cancer with chemotherapy)

About 20 percent to 40 percent of patients who do not have artificial heart valves and who do not use intravenous drugs have no identifiable heart abnormality that clearly would increase their risk for endocarditis. In the 10 percent to 20 percent of patients who have artificial heart valves, endocarditis that follows within 60 days of valve surgery often is caused by a staphylococcus, while endocarditis that occurs later most frequently is caused by a streptococcus.


Symptoms of acute endocarditis include:

  • High fever
  • Chest pain
  • Shortness of breath
  • Cough
  • Small broken blood vessels (hemorrhages) on the palms and soles of the feet

If severe heart damage causes shock, the patient may collapse suddenly, have a rapid pulse and have pale, cool skin.

Symptoms of subacute endocarditis include:

  • Low-grade fever (less than 102.9 degrees Fahrenheit)
  • Chills
  • Night sweats
  • Pain in muscles and joints
  • A persistent tired feeling
  • Headache
  • Shortness of breath
  • Poor appetite
  • Weight loss
  • Small, tender nodules on the fingers or toes
  • Tiny broken blood vessels on the whites of the eyes, the palate, inside the cheeks, on the chest or on the fingers and toes


Your doctor will review your medical history with particular attention to possible risk factors for endocarditis, including congenital heart disease, rheumatic fever, an artificial heart valve or pacemaker, a history of IV drug use, and a history of chronic illness. Your doctor also will ask whether you have ever been told that you have a heart murmur and whether you have had any recent medical or dental procedure in which bacteria might have had an opportunity to entire your bloodstream (dental scaling, periodontal surgery, professional teeth cleaning, bronchoscopy, certain diagnostic tests of the genitourinary tract, colonoscopy).

Additional evidence for the diagnosis will come from your physical examination, when your doctor checks for fever, skin symptoms of endocarditis (tiny hemorrhages in the skin, tender nodules on finger and toes) and a heart murmur, which indicates possible heart-valve damage. Additional testing includes:

  • Blood cultures — In these tests, several blood samples will be drawn over a 24-hour period. These blood samples will be added to culture bottles that contain special nutrients to aid bacterial growth. If bacteria are living in the patient’s bloodstream, they will grow inside the culture bottles in the laboratory. Once bacteria grow, the specific species can be identified, and it can be tested for its sensitivity to various types of antibiotics. Results of this sensitivity testing will guide the doctor in selecting the specific antibiotic that will be most effective in treating the patient’s endocarditis.
  • Echocardiography — In this test, sound waves are used to outline the structure of the heart, the heart chambers and heart valves. By using echocardiography, your doctor can check for vegetations (abnormal growths that contain infecting organisms) on the heart valves or elsewhere inside the heart. He or she also can look for abscesses inside the heart and for signs of damage to natural or artificial heart valves. The best type of echocardiography for evaluating heart valves is transesophageal echocardiography, in which a tube is inserted through your mouth, allowing images of the heart to be obtained from just behind it. This test may be recommended if the diagnosis remains uncertain after conventional echocardiography. Transesophageal echocardiography is also a much better test for evaluating artificial heart valves.
  • Serological tests — These are blood tests that look for evidence of immune-system activity, which is a sign of infection. Serological tests may be helpful in the small percentage of patients with endocarditis whose blood cultures do not show bacterial growth.

Expected Duration

Symptoms of acute endocarditis usually begin suddenly and progress rapidly. It is an infection that can evolve dramatically over a few days. Subacute endocarditis evolves more slowly, and its milder symptoms can be present for weeks or months before the illness is suspected.


If you are at high risk of endocarditis because of a damaged heart valve or other medical problem, inform your doctor and dentist. To prevent endocarditis, your doctor and dentist may prescribe special antibiotics before you undergo any medical or dental procedure in which bacteria have a chance of entering your blood. Antibiotics usually are administered to people with artificial valves, people who had endocarditis in the past and people with other high-risk conditions. People with mitral valve prolapse and many milder conditions may not require antibiotics.

In general, antibiotics are given one to two hours before a high-risk procedure, and up to eight hours afterward. Before a dental procedure, an antiseptic mouth rinse also can be used, especially one containing chlorhexidine or povidone-iodine.

Whether your heart valves are normal, damaged or artificial, you can help prevent endocarditis by avoiding IV drug use.


When endocarditis is caused by a bacterial infection, it usually is treated with two to six weeks of antibiotics, such as penicillins, cephalosporins, gentamicin (Garamycin, Gentamar, G-Myticin) or vancomycin (Vancocin). The type of antibiotic and the length of therapy depend on the results of the patient’s blood cultures, which identify the species of infecting bacteria and its sensitivity to specific antibiotics. In most cases, antibiotic treatment is given intravenously (through a vein) while the patient is hospitalized. However, certain highly motivated patients who have Streptococcus viridans endocarditis and stable heart function sometimes can be treated at home.

In some patients with endocarditis, the infected heart valve must be replaced surgically. There are several indications for valve replacement, including:

  • Damage to the aortic or mitral valve that is severe enough to cause regurgitation (backflow of blood through the valve) with heart failure
  • Valve dysfunction and persistent infection after seven to 10 days of appropriate antibiotic therapy
  • A vegetation (abnormal growth) larger than 10 millimeters (seen on echocardiography) clinging to a heart valve
  • Endocarditis caused by a fungus rather than bacteria — Fungal endocarditis often responds poorly to intravenous antifungal medications.

When To Call A Professional

Call your doctor whenever you experience symptoms of acute or subacute endocarditis, especially if you have a history of heart-valve damage, a known heart murmur or an implanted device in your heart (artificial valve or pacemaker wire).


With prompt diagnosis and proper medical treatment, about 90 percent of patients with bacterial endocarditis recover. Those whose endocarditis affects the right side of the heart usually have a better prognosis than those with left-side involvement. In cases in which endocarditis is caused by fungi, the prognosis is usually worse than for bacterial endocarditis.

Some complications of endocarditis include congestive heart failure; emboli (floating blood clots in the bloodstream) that lodge in the brain, lungs or coronary arteries; and kidney problems. If acute endocarditis remains untreated, it can be fatal in less than six weeks. Untreated subacute endocarditis can cause death within six weeks to one year.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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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.