Infectious endocarditis

Question 1

What is infectious endocarditis?

Answer 1

Infection and inflammation of the endothelium of the heart secondary to bacteraemia

Question 2

How does infectious endocarditis occur?

Answer 2

Abnormal/damaged endothelial surface of heart valve allows platelet adhesion and thrombus formation, allowing bacteria to attach, multiply and damage the valve.

Immune response to bacteria in vegetation on valve can also cause swelling and tissue damage

Question 3

What causes infectious endocarditis?

Answer 3

Streptococcus sanguis (more commonly)
- A viridans streptococci
- Alpha haemolytic

Staphylococcus aureus
Staphylococcus epidermidis
Pseudomonas aeruginosa

Question 4

What is the route of infection for infectious endocarditis?

Answer 4

Streptococcus sanguis
- Mouth

Staphylococcus aureus and Staphylococcus epidermidis
- Blood borne through wound infection

Question 5

What are the two categorisations of infectious endocarditis?

Which one is more severe?

Answer 5

Subacute bacterial endocarditis
- Damage done only by immune system response
- Slow progression of illness (weeks to months) and less severe
- Caused by less virulent pathogens
Staphylococcus epidermidis, Streptococcus sanguis

Acute bacterial endocarditis
- Damage done by bacteria and immune response
- Fast progression of illness (Days to weeks) and more severe >50% mortality
- Caused by more virulent bacteria
Staphylococcus aureus

Question 6

What is a characteristic surface symptom of infectious endocarditis?

Answer 6

Embolic lesions resulting in valve vegetation breaking off and travelling around the body to smaller vessels

Question 7

What are some tests that can be used to diagnose infectious endocarditis?

Answer 7

Echocardiographic evidence of vegetation

Tests for bacteraemia

Positive blood cultures for typical microorganisms
- Streptococcus sanguis
- Staphylococcus aureus
- Staphylococcus epidermidis

Evidence of emboli

Question 8

What is the treatment for infectious endocarditis?

Answer 8

High dose of organism dependent antibiotic for 4-6 weeks

Repair/removal and replacement of damaged heart valve

Bacteraemia risk reduction for patients with abnormal heart valves
- e.g. prophylactic antibiotics for dental work