Infective Endocarditis

Question 1

What is the mechanism of IE

Answer 1

• Bacteraemia + endocardial insult e.g. turbulent blood flow or mechanical valve
• This leads to the colonisation of bacteria around the valves and formation of vegetations
• Particles from these vegetations can break off and cause septic emboli.
• The vegetations themselves can also compromise heart function

Question 2

What risk factors predispose to IE

Answer 2

• Structural heart disease e.g. from rheumatic heart disease
• Prosthetic valve
• Congenital heart disease
• IVDU
• Immunocompromised
• Older age

Question 3

What systems can IE affect

Answer 3

• Spleen: splenic abscess or infarct
• Neuro: stroke or TIA from emboli, or abscess
• Cardio: acute heart failure, tricuspid valve disease, cardiac abscess, PE
• Renal: glomerulonephritis

Question 4

What is the presentation of IE

Answer 4

• Fever
• Fatigue
• Chest pain
• SOB
• Haematuria if renal involvement
• Heart murmur
• Peripheral signs of IE

Question 5

What are Janeway lesions

Answer 5

Painless lesions on palms and soles (thenar eminence) due to micro emboli

Question 6

What are Oslers nodes

Answer 6

Painful erythematous nodules on the tips of the fingers and toes due to local immunological response

Question 7

What are Roth spots

Answer 7

White centred retinal haemorrhage due to retinal capillary rupture

Question 8

What organisms most commonly cause IE

Answer 8

Staph Aureus = most common
- Strep viridans
- Enterococcus
- HACEK
- Fungi (candida) - rare

Question 9

What criteria do we use to stratify likelihood of IE

Answer 9

Modified Duke’s criteria

Question 10

Duke’s major criteria

Answer 10

• Persistently positive blood culture for typical organism
• ECHO shows vegetations, abscess or dehiscence of prosthetic valve
• New murmur
  -Coxiella Burnetti Infection

Question 11

Duke’s minor criteria

Answer 11

• Underlying heart condition or IVDU
• Fever greater than 38
• Evidence of emboli
• Immunologic evidence: glomerulonephritis, oslers nodes, roth spots
• Positive blood cultures not meeting specific criteria

Question 12

Definite IE

Answer 12

• 2 major
• 1 major + 3 minor
• 5 minor
  + gram positive stain or culture

Question 13

Possible IE

Answer 13

• 1 major and 1-2 minor
• 3 minor

Question 14

Rejected IE

Answer 14

• Resolution after less than 4 days ABx
• No evidence of infection following surgery

Question 15

IE investigations

Answer 15

• Blood cultures: 3 samples taken at 30 min intervals from different sites
• Echo: TOE preferred
• ECG: typically normal, aortic abscess may show PR prolongation

Question 16

What is the management of IE

Answer 16

• IV ABx - intially empirical however then guided by culutes
• Surgery if severely indicated

Question 17

What ABX do we use in IE

Answer 17

• Empirical: amoxicillin if native valve, vancomycin + rifampicin + low dose gentamicin if prosthetic
• Staph: Flucloxacillin, add rifampicin + low dose gentamicin if prosthetic valve

Question 18

When do we do surgery in IE

Answer 18

• Heart failure
• Aortic root abscess formation
• Severe valve incompetence
• Recurrent emboli