Infective Endocarditis

Question 1

What are some risk factors of infective endocarditis? (5)

Answer 1

• Intravenous drug use
• Structural heart pathology (see below)
• Chronic kidney disease (particularly on dialysis)
• Immunocompromised (e.g., cancer, HIV or immunosuppressive medications)
• History of infective endocarditis

Question 2

What structural pathologies can lead to increased risk of endocarditis? (5)

Answer 2

• Valvular heart disease
• Congenital heart disease
• Hypertrophic cardiomyopathy
• Prosthetic heart valves
• Implantable cardiac devices (e.g., pacemakers)

Question 3

What are the 3 main bacterial causes of infective endocarditis?

Answer 3

Staphylococcus aureus
Streptococcus
Enterococcus

Question 4

What are the presenting symptoms of infective endocarditis? (5)

Answer 4

Non specific signs of infection
• Fever
• Fatigue
• Night sweats
• Muscle aches
• Anorexia (loss of appetite)

Question 5

What are the signs of infective endocarditis? (8)

Answer 5

• New or “changing” heart murmur
• Splinter haemorrhages (thin red-brown lines along the fingernails)
• Petechiae (small non-blanching red/brown spots) on the trunk, limbs, oral mucosa or conjunctiva
• Janeway lesions (painless red flat macules on the palms of the hands and soles of the feet)
• Osler’s nodes (tender red/purple nodules on the pads of the fingers and toes)
• Roth spots (haemorrhages on the retina seen during fundoscopy)
• Splenomegaly (in longstanding disease)
• Finger clubbing (in longstanding disease)

Question 6

How should blood cultures be done when investigating infective endocarditis?

Answer 6

Take before starting abx

Three blood culture samples are recommended, usually separated by at least 6 hours and taken from different sites.

Hal may be shorter if urgently need abx

Question 7

What is the usually imaging used in infective endocarditis?

Answer 7

Echo
Can see vegetations on the valves

Question 8

What special imaging is used in patients with prosthetic valves to look for infective endocarditis? (2)

Answer 8

• 18F-FDG PET/CT
SPECT-CT

Question 9

What is the modified dukes criteria used for?

Answer 9

Diagnosing infective endocarditis

Question 10

What are the criteria for the modified dukes criteria?

Answer 10

• One major plus three minor criteria
• Five minor criteria

Major criteria are:
• Persistently positive blood cultures (typical bacteria on multiple cultures)
• Specific imaging findings (e.g., a vegetation seen on the echocardiogram)

Minor criteria are:
• Predisposition (e.g., IV drug use or heart valve pathology)
• Fever above 38°C
• Vascular phenomena (e.g., splenic infarction, intracranial haemorrhage and Janeway lesions)
• Immunological phenomena (e.g., Osler’s nodes, Roth spots and glomerulonephritis)
• Microbiological phenomena (e.g., positive cultures not qualifying as a major criterion)

Question 11

What is the main treatment for infective endocarditis?
How long should it be given for?

Answer 11

IV broad spectrum abx e.g. amoxicillin and optional gentamicin

• 4 weeks for with native heart valves 
• 6 weeks for patients with prosthetic heart valves

Question 12

When may surgery be required in infective endocarditis? (3)

Answer 12

• Heart failure relating to valve pathology
• Large vegetations or abscesses
• Infections not responding to antibiotics

Question 13

What are the key complications of infective endocarditis? (4)

Answer 13

• Heart valve damage, causing regurgitation
• Heart failure
• Infective and non-infective emboli (causing abscesses, strokes and splenic infarction)
Glomerulonephritis, causing renal impairment