Infective Endocarditis

Question 1

Define Infective Endocarditis

Answer 1

Inflammation of the endocardium and the valves of the heart caused by bacterial infection

Question 2

What causes infective endocarditis?

Answer 2

There are a number of bacteria which can cause infective endocarditis. However, the most common causative pathogen is Staphylococcus aureus

Question 3

Who is infective endocarditis more common in?

Answer 3

catheterised patients and IV drug users

Question 4

What are other pathogens that cause infective endocarditis?

Answer 4

Streptococcus viridans*
Streptococcus Bovis (associated with the colon)*
Staphylococcus epidermidis*

Enterococcus faecalis
Coxiella burnetta
Aspergillus
Candida
Brucella
Histoplasma

Question 5

Describe the pathophysiology of infective endocarditis

Answer 5

• The infecting pathogen causes inflammation and can damage the valves
• This usually occurs more commonly in already damaged endocardium or congenital heart conditions
• Vegetations can form on the valves (infecting pathogen + fibrin + platelets) as a result, causing additional damage to the valves or emboli formation

Question 6

What type of valves are prone to clots?

Answer 6

Prosthetic heart valves

Question 7

What are the main signs/ symptoms of infective endocarditis?

Answer 7

New murmur + fever -> endocarditis, until proven otherwise

Question 8

How is infective endocarditis diagnosed?

Answer 8

Duke Jones criteria – set of clinical criteria to definitively diagnose infective endocarditis:
2 major + 1 minor
OR
1 major + 3 minor
OR
5 minor

Question 9

What are the major criteria for diagnosing infective endocarditis?

Answer 9

• Positive blood culture >2 times 12 hrs apart
• Echocardiographic evidence of endocardial involvement

Question 10

What are the minor criteria for diagnosing infective endocarditis?

Answer 10

• Predisposing heart condition OR IV drug use
• Fever >38C
• Immunological phenomena – Osler’s nodes, Roth spots
• Microbiological evidence (that does not meet major criteria for blood culture)
• Embolic phenomenon

Question 11

How is infective endocarditis treated?

Answer 11

• Identify causative pathogen
• IV antibiotics
  If severe valvular abnormalities are caused due to IE, consider surgical involvement (valvular repair)

Question 12

What is the mnemonic for remembering Duke Jones criteria?

Answer 12

BE TIMER

Major
B- Blood culture positive >2 times 12 hrs apart
E- Echocardiographic evidence of endocardial involvement

Minor
TIMER
T-Temp (fever >38 degree)
I- Immunological phenomena – Osler’s nodes, Roth spots
M- Microbiological evidence (that does not meet major criteria for blood culture)
E- Embolic phenomenon
R- Risk factors (congenital heart condition or IV drug use)