Infective Endocarditis

Question 1

What is IE?

Answer 1

Microbiological colonisation of the heart valves or endocardium, giving rise to vegetations.

NB - the valves don’t receive their own blood supply so it is difficult for WBCs and also medication to reach the area.

Question 2

How can IE cause systemic symptoms?

Answer 2

The microbiological vegetations seed into the circulation causing fever and systemic symptoms

Question 3

Which side of the heart is usually involved?

Answer 3

LEFT - 95%, this also has a worse mortality than right-sided

Question 4

In which cases is right-sided endocarditis often seen?

Answer 4

IVDU’s (usually due to staph aureus) and immunocompromised patients

Question 5

Name some risk factors for IE

Answer 5

• IV drug use
• Congenital valvular abnormalities
• Prosthetic valve replacement
• Mitral valve prolapse
• Rheumatic heart disease
• Previous IE
• Hypertrophic cardiomyopathy
• Invasive dental or surgical procedures (provide route of entry for bacteria)

Question 6

What are the main causative organisms?

Answer 6

Oral strep. viridans (most common in community)
Skin staph. aureus (most common in hospital)

Also enterococci (through gut) and HACEK group

Question 7

What are the symptoms of IE?

Answer 7

CLASSICAL TRIAD:

• Persistent PUO
• New/changing murmur
• Embolic phenomena (incl. strokes, pulmonary emboli, limb ischaemia, splinter haemmorhages, petechiae)

Also causes the usual systemic symptoms and anaemia

Question 8

Describe some signs on the hands of IE

Answer 8

Splinter haemmorhages - vertical blood clots on nails
Janeway lesions - flat painless red-blue macules (vascular)
Oslers nodes - painful erythematous nodules (immunological)

Question 9

What investigations are done?

Answer 9

• Blood cultures (at least 3 sets over 6 hours apart)
• Echocardiogram (not that sensitive)
• FBC

Question 10

What are the diagnostic criteria for IE?

Answer 10

You need 2 major alone, 1 major and 3 minor, or 5 minor:

MAJOR

• Positive blood culture for typical organism
• Echo showing typical mass on valve

MINOR
- Underlying heart disease or IVDU
- Fever >38C
- Vascular phenomena (arterial emboli, pulmonary infarcts, intracranial blood, conjunctival haemorrhages, janeways lesions)
- Immunological phenomena (glomerulonephritis, oslers nodes, roth spots on retina)
- Positive blood culture (not meeting major criteria)
Echo features (not meeting major criteria)

Question 11

How is non-severe sepsis of a native valve treated?

Answer 11

IV amoxicillin and IV gentamicin

Question 12

How is severe sepsis of a native valve treated?

Answer 12

IV vancomycin and IV gentamicin

Question 13

How is sepsis of a prosthetic valve treated?

Answer 13

IV vancomycin, IV gentamicin and PO/IV rifampicin

Question 14

What are some potential complications of IE?

Answer 14

• Congestive heart failure
• Emboli/stroke
• Abscess or disseminated infection
• MI/arrhythmia
• Glomerulonephritis

Question 15

Why is there a relationship between endocarditis and stroke?

Answer 15

Turbulent blood flow in the heart can lead to formation of emboli that go to the brain

• this is a common feature of enterococcal endocarditis

Question 16

What are the problems with gentamicin?

Answer 16

Toxic to kidneys and hearing

Question 17

What is the most common organism in IVDU?

Answer 17

Staph aureus

Question 18

What is the most common organism in people with prosthetic valves?

Answer 18

Staph epidermidis

Question 19

Before starting vancomycin/gentamicin what investigation should be done?

Answer 19

U and E - renotoxic