What is Bacterial Endocarditis?

Infective (bacterial) endocarditis is an infection of either the heart’s inner lining (endocardium) or the heart valves.

Infective endocarditis (IE) is uncommon, although some individuals with heart conditions may be at greater risk of developing IE.

What are the causes?

Infective endocarditis (IE) is caused by:

    • Bacteria i.e. streptococci and staphylococci (most common)
    • Rickettsia
    • Fungus (rare)

How does it occur?

Certain bacteria are normally found in the oral cavity, upper respiratory tract, intestines, urinary tract and skin.

For any reason, these bacteria can enter the blood stream and cause what is called bacteremia. This infected blood flows through the body and can settle on abnormal or damaged heart valves or endocardium. The bacteria in the blood begin to damage the heart valves. Bacteria can start collecting and piling up on these damaged valves to form what is called vegetations. Vegetations can further disrupt blood flow through the heart valves.

Bacteremia is common after many invasive procedures including dental or surgical procedures.


Who is at risk?

Those at risk of developing infective endocarditis include:

    • Individuals with damaged valves or those with a damaged endothelium caused by high pressures jets of blood due to septal defects (congenital heart defects), valve stenosis, or valve regurgitation may be at higher risk of IE
    • Following cardiac surgery using prosthetic valves and other prosthetic material or intraoperative infection
    • Intravenous drug users
    • Previous history of endocarditis

If you have any of the above conditions, you may need to take antibiotics before certain dental or surgical procedures for prophylactic treatment.

If you are at risk of IE, maintaining good oral hygiene is essential for prevention.

Antibiotics before dental procedures are only recommended for patients with the highest risk of infected endocarditis and who would gain the most from IE prevention.

Recommended regimens:

A single dose of antibiotic prophylaxis should be administered before the patient’s procedure.

If not possible before, prophylaxis can be administered up to 2 hours after the procedure.

Patients undergoing cardiac surgery

  • A dental evaluation and treatment is recommended before cardiac valvular surgery or the replacement/repair of CAD. This decreases the incidence of late prosthetic valve endocarditis.
  • Patients who are undergoing prosthetic heart valve surgery or prosthetic intravascular/ intracardiac materials are at risk of developing infection. Prophylactic antibiotics are recommended for these procedures because the morbidity and mortality risk and infection are high.

Antibiotic prophylaxis is not required in patients who have undergone coronary artery bypass graft surgery or percutaneous intervention with stent implantation.


Dental procedures

  • Antibiotic prophylaxis is recommended for patients undergoing dental procedures involving the gingival tissue or periapical region of a tooth who has at least one of the following conditions:

– Prosthetic heart valve

– Previous infective endocarditis

– Congenital heart disease

– Heart transplantation recipients who have developed cardiac valvulopathy


Respiratory tract procedures

  • Many respiratory tract procedures cause transient bacteremia with an array of organisms, although there is no supporting data demonstrating the link between procedures and IE.

The AHA does not recommend antibiotic prophylaxis for bronchoscopy unless the procedure involves an incision of the respiratory tract mucosa.


Gastrointestinal (GI) or Genitourinary (GU) tract

  • Enterococci is a normal bacteria found in the intestinal flora. During an infection of the GI tract, enterococci are likely to cause infective endocarditis.

The AHA does not recommend prophylactic antibiotics to prevent IE for patients undergoing GI or GU procedures. There is no supporting data showing that the administration of prophylactic antibiotics for GI or GU procedures prevents infective endocarditis.