Infective Endocarditis

Definition

Infective endocarditis (IE) is an infection of the inner lining of the blood vessels and heart (endocardium). It often affects the heart valves and the ensuing inflammation may cause scarring and distortion of the heart valves. Endocarditis may be categorised into acute endocarditis (usually highly virulent pathogens which may infect normal valves), subacute endocarditis (low virulent pathogens infecting pre-existing abnormal valves) or prosthetic valve endocarditis. Most people who develop infective endocarditis have pre-existing heart valve problems which allow infection to occur.

Common pathogens causing IE

  • Acute: Staphylococcus aureus is the most common cause and risk factors include intravenous drug abuse, open heart surgery and septicaemia. Normal heart valves may be involved and cause rapid destructive lesions.
  • Subacute: Streptococcus viridans, other oral StreptococciEnterococciand the HACEK group of organisms (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella) are important pathogens causing subacute IE. These pathogens originate from the skin, gut and the oral cavity. Abnormal heart valves including those with congenital heart defects may be infected.
  • Prosthetic valve: Staphylococcus aureus and Staphylococcus epidermidiscan attack prosthetic heart valves or pacemakers and cause inflammation and scarring.

Clinical Symptoms

  • High fever or chills with acute IE or low grade fever and sweats with subacute IE
  • Systemic symptoms like unexplained weight loss, headache, myalgia and fatigue
  • Cough, breathlessness and reduced effort tolerance
  • Joint pains
  • Blood in the urine
  • Painless macules on the palms (called Janeway lesions)
  • Painful small red nodules on the fingertips (called Osler’s nodes)
  • Tiny purple or red spots on the skin or inside your mouth (called petechiae)
  • Splinter haemorrhages (dark red lines in the nailbeds)
  • Complications such as swelling in the legs, ankles or feet may indicate heart failure

 Diagnostic Tests

  • Blood count to check for anaemia or high white blood cell count indicating infection
  • Blood cultures are important to determine which bacteria is causing the infection. This helps to determine the most appropriate antibiotic needed
  • Transthoracic and Transesophageal echocardiogram. Echocardiography utilizes a probe to emit sound waves to produce images of the heart and valve structures. In the transthoracic approach, the probe is placed over the chest wall and in the transesophageal approach the probe is passed through the mouth and into the oesophagus where certain heart structures are better visualized.
  • Electrocardiogram (ECG) to check for any irregular heart rhythm
  • Chest X-Ray to see if heart is enlarged or if infection has spread to the lungs

Treatment

Intravenous antibiotics are required for many weeks and may vary from 2-6 weeks (duration depends on the organism causing infection and the severity of illness). Surgery may be required if there is persistent or uncontrolled infection or to replace a damaged valve that has caused heart failure.

Prevention

Infections in the mouth that occur from poor oral hygiene and recent dental surgery may increase the risk of infective endocarditis. It is thus important to have good dental health with regular flossing, brushing teeth and dental check-ups.

For patients with pre-existing valvular heart disease and who need to undergo dental or surgical procedures, they must inform the dentist / doctor concerned as prophylactic antibiotics may be required. If required, a penicillin based antibiotic is administered orally one hour before the dental procedure.

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