Infective endocarditis

Question 1

What symptoms when seen together should be treated as infective endocarditis until proven otherwise

Answer 1

Fever + new murmur

Question 2

Which individuals are considered at risk of IE?

Answer 2

1. Past IE
2. Past rheumatic fever
3. IV drug abuser
4. Damaged or replaced valve
5. Structural congenital heart disease
6. Hypertrophic cardiomyopathy

Question 3

In individuals at known risk of IE, what symptom(s) should prompt immediate blood cultures?

Answer 3

Fever lasting >1 week

Question 4

What is infective endocarditis?

Answer 4

An inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves.

Question 5

What is the chief cause of acute IE?

Answer 5

Staph. aureus

Question 6

What are risk factors for acute IE?

Answer 6

Dermatitis
IV injections
Renal failure
Organ transplantation
DM
Post-op wounds

Question 7

What is the usual entry site for the infective agent in acute IE

Answer 7

Skin

Question 8

How does acute IE present?

Answer 8

Acute heart failure with or without emboli

Question 9

How is IE classified?

Answer 9

Acute IE: Occurs on normal valves. Occurs suddenly over days to weeks

Subacute IE: Occurs on abnormal valves. Often due to streptococci of low virulence and causes mild to moderate illness which progresses slowly over weeks and months

Question 10

What are the risk factors for subacute IE?

Answer 10

Aortic or mitral valve disease
Tricuspid valves in IV drug users
Coarctation
Patent ductus ateriosus
VSD
Prosthetic valves

Question 11

How is IE on prosthetic valves classified?

Answer 11

Early: within 60 days of valve surgery; poor prognosis
Late: haematogenous

Question 12

What are the causes of IE?

Answer 12

Bacteraemia
Strep. viridans is a common cause (>35%)
Other causes:
- Enterococci
-Staph aureus/epidermidis
-Diptheroids
-Rarely HACEK gram negative bacteria (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella)

Question 13

What are the main types of signs seen in IE?

Answer 13

Septic signs
Cardiac signs due to cardiac lesions
Immune complex deposition
Embolic phenomena

Question 14

What septic signs are seen in IE?

Answer 14

Fever
Rigours
Night sweats
Malaise
Weight loss
Anaemia
Splenomegaly
Clubbing

Question 15

What signs of cardiac lesions are seen in IE?

Answer 15

Any new murmur or a changing pre existing murmur should raise the suspicion of endocarditis
Vegetations may cause valve destruction and severe regurgitation or valve obstruction
An aortic abscess causes prolongation of the PR interval and may lead to complete AV block
LVF is a common cause of death

Question 16

What signs of immune complex deposition are seen in IE?

Answer 16

Vasculitis
Microscopic haematuria
Glomerulonephritis
Acute renal failure
Roth spots
Splinter haemorrhages
Osler nodes

Question 17

What are Roth spots?

Answer 17

Boat-shaped retinal haemorrhage with pale centre

Question 18

What signs of emboli are seen in IE?

Answer 18

Abscesses in the relevant organ e.g. brain, heart, kidney, spleen or skin- termed Janeway lesions

Question 19

What features are pathognomonic (specific)

for IE

Answer 19

Janeway lesions

Osler’s nodes

Question 20

How can you differentiate between Osler’s nodes and Janeway lesions?

Answer 20

Osler nodes: painful, usually seen on pads of fingers and toes
Janeway lesions: non-tender, usually seen on the palms or soles of feet

Question 21

What are the diagnostic criteria for IE?

Answer 21

Duke Criteria: 2 major or 1 major and 3 minor or all 5 minor criteria are diagnostic

Question 22

What are the major Duke criteria for IE?

Answer 22

Positive blood culture:

• Typical organism in 2 separate cultures
• Persistently positive blood cultures e.g. 3>12h apart (or majority if ≥4)

Endocardium involved:
-Positive echocardiogram for vegetation, abscess, dehiscence of prosthetic valve
OR
-New valvular regurgitation (change in murmur is not sufficient)

Question 23

What are the major Duke criteria for IE?

Answer 23

Predisposition (cardiac lesion; IV drug abuse)
Fever >38 degrees C
Vascular/immunological signs
Positive blood culture that does not meet major criteria
Positive echocardiogram that does not meet major criteria

Question 24

What is more common, acute or subacute infective endocarditis?

Answer 24

SBE

Question 25

What features might be seen on a blood test in IE?

Answer 25

Normochromic, normocytic anaemia
Neutrophilia
High CRP/ESR

Question 26

What tests should be done to confirm diagnosis of IE?

Answer 26

• Blood cultures: 3 sets at different times from different sites at peak of fever
• Blood tests
• Urinalysis- for microscopic haematuria
• CXR- cardiomegaly
• ECG- long PR interval
• Echo- TTE may show vegetations if >2cm. TOE is more sensitive

Question 27

While awaiting results of blood cultures, which antibiotics should be used for IE?

Answer 27

IV benzylpenicillin and gentamycin

Question 28

What antibiotics should be be given if staphylococcal endocarditis is suspected?

Answer 28

Vancomycin and gentamycin

Question 29

What antibiotics should be be given if gram negative endocarditis is suspected?

Answer 29

Meropenem + vancomycin

Question 30

When should surgery be considered for treatment of IE?

Answer 30

Heart failure
Valvular obstruction
Repeated emboli
Fungal endocarditis
Persistent bacteraemia
Myocardial abscess
Unstable infected prosthetic valve