Infective endocarditis

Question 1

What is infective endocarditis?

Answer 1

• Microbial infection of a native or prosthetic heart valve or mural endocardium.
• leading to the formation of vegetations and tissue destruction.
• Multisystem disorder caused by haematogenous spread

Question 2

What are the risk factors for endocarditis?

Answer 2

1. Prosthetic heart valves
2. IV drug use
3. Congenital heart disease
4. Previous endocarditis
5. Damaged heart valves

Question 3

What are the clinical manifestations of endocarditis?

Answer 3

1. Non-specific presentation: weight loss, lethargy, fevers.
2. Valvular involvement: New murmur, CCF (valve failure)
3. Bacteraemia: Fever, raised inflammatory markers.
4. Embolic phenomena: Septic emboli (CVA, MI, PE, abdominal viscera ischaemia), peripheral stigmata (Janeway lesions, splinter haemorrhages).
5. Immune-complex formation:
   - Renal (interstitial nephritis and glomerulonephritis).
   - Synovitis
   - Myocarditis
   - Osler nodes (tender)
   - Roth’s spots

Question 4

What are the causative organisms in infective endocarditis?

Answer 4

1. Bacterial
   - S. aureus
   - streptococci
   - enterococci
   - Gram-negative bacilli
   - HACEK (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella).
2. Fungal (mainly prosthetic valves).

Question 5

How is endocarditis diagnosed?

Answer 5

Modified Duke criteria

Clinical criteria include:

• 2 Major
• 1 major and 3 minor
• 5 minor

Major criteria:

i) persistent blood culture with IE organism
ii) echo changes or new murmur

Minor criteria:

i) predisposing condition/risk factor
ii) fevers >38oC
iii) vascular phenomena
iv) immunological phenomena
v) microbiological evidence not meeting major criteria

Question 6

How is infective endocarditis treated?

Answer 6

1. Resuscitation
2. Investigations:
   - TTE/TOE
   - ECG
   - bloods inc inflammatory markers and renal function
   - blood cultures (3 sets from different sites)
   - urinalysis
   - CXR
3. ABx - liase with micro, often fluclox and gent.
4. Cardiac surgery:
   - valve failure
   - myocardial abscess or fistula
   - fungal infection
   - high risk of emboli (vegetations >10mm)
   - persistent positive blood cultures despite treatment