Infective Endocarditis

Question 1

What is endocarditis?

Answer 1

an endovascular infection of cardiovascular structures including cardiac valves, atrial and ventricular endocardium, large intrathoracic vessels and intracardiac foreign bodies

Question 2

What is the approx. mortality of untreated endocarditis?

Answer 2

100%

Question 3

True or false: fever + new murmur = infective endocarditis until proven otherwise

Answer 3

true

Question 4

What is infective endocarditis?

Answer 4

Infective endocarditis is when the heart’s inner lining (the endocardium) becomes inflamed secondary to an infection.

Question 5

Is infective endocarditis more common in men or women?

Answer 5

Men

Question 6

What are the 3 layers of the heart?

Answer 6

An outer epicardium (connective tissue and fat)
A middle muscular myocardium
An inner endocardium

Question 7

Give 6 potential causes of bacteraemia that may lead to endocarditis:

Answer 7

1) poor dental hygiene
2) IV drug use
3) soft tissue infection
4) dental treatments
5) intravascular cannulae infection
6) cardiac surgery or permanent pacemakers

Question 8

How does damaged endothelium increase endocarditis risk?

Answer 8

damaged endothelium promotes platelet and fibrin deposition which allows organisms to adhere and grow, leaving to the formation of an infected vegetation

Question 9

Give two reasons for abnormal cardiac endothelium:

Answer 9

1) valvular lesions creating non-laminar flow
2) septal defects or a patent ductus arteriosus

Question 10

What two cardiac structures are most commonly affected by infective endocarditis?

Answer 10

1) mitral valve
2) aortic valve

Question 11

Is endocarditis most commonly left-sided or right-sided?

Answer 11

Left-sided
Only 5-10% are right-sided

Question 12

What cardiac region is most commonly affected by infective endocarditis in IV drug users?

Answer 12

right-sided chambers

Question 13

What is the most causative bacteria for infective endocarditis?

Answer 13

Staphylococcus aureus

Question 14

Give three ways in which S. aureus can reach the heart:

Answer 14

1) infection of prosthetic valves
2) IV drug user contamination
3) infected indwelling catheters

Question 15

What % of infective endocarditis is caused by Streptococcus viridans in developing countries?

Answer 15

50%

Question 16

Give two examples of S. viridans bacteria:

Answer 16

1) Streptococcus mitis
2) Streptococcus sanguinis

Question 17

Where is S. viridans usually found?

Answer 17

Mouth (particularly in dental plaque)

Question 18

Give 2 factors that increase risk of S. viridans infective endocarditis?

Answer 18

1) poor dental hygiene
2) dental procedure

Question 19

Give two ways in which Staph. epidermidis can reach the heart:

Answer 19

1) colonising indwelling lines
2) colonising prosthetic valves

Question 20

What bacteria is the most common cause of infective endocarditis immediately after surgery?

Answer 20

Staphylococcus epidermidis

Question 21

What bacteria associated with colorectal cancer causes infective endocarditis?

Answer 21

Streptococcus bovis

Question 22

Give two examples of non-infective endocarditis:

Answer 22

1) Libman-Sacks endocarditis
2) Non-bacterial thrombotic endocarditis

Question 23

What is Libman-Sacks endocarditis?

Answer 23

endocarditis associated with SLE

Question 24

What is non-bacteria thrombotic endocarditis?

Answer 24

small, sterile vegetations deposited on valve leaflets causing inflammation of the endocardium

Question 25

Give the overall framework of the Modified Duke criteria

Answer 25

either of the following confirms infective endocarditis diagnosis
1) positive microbiology/histology test on vegetations
2) patient fits two points of the major criteria
3) patient fits one point of the major and 3 points of the minor criteria
4) patient fits five points of the minor criteria

Question 26

Give 4 examples of major points from the Modified Duke criteria:

Answer 26

1) two positive blood cultures consistent with endocarditis bacteria
2) positive molecular assays for gene targets
3) positive echocardiogram (e.g. abscess, vegetation, new valvular regurgitation)
4) new valvular regurgitation

Question 27

Give 4 examples of minor points listed in the Modified Duke criteria:

Answer 27

1) predisposing heart condition or IV drug user
2) fever >38 degrees C
3) vascular signs e.g. splinter haemorrhages
4) immunological signs e.g. Osler’s nodes

Question 28

Give 8 potential clinical features of infective endocarditis:

Answer 28

1) fever
2) heart murmur (new)
3) petechiae
4) Janeway lesions
5) Osler’s nodes
6) splinter haemorrhages
7) Roth spots
8) haematuria, glomerulonephritis and suspected renal infarction

Question 29

What is petechiae?

Answer 29

small red/purple spots due to capillary haemorrhage

Question 30

What are Janeway lesions?

Answer 30

irregular, painless erythematous macules found on the thenar and hypothenar eminence

Question 31

What are Osler’s nodes?

Answer 31

small, tender, red/purple nodules on the pulp of finger tips

Question 32

What are roth spots?

Answer 32

Retinal hemorrhages with pale centers

Question 33

How many blood cultures should be taken when investigating infective endocarditis?

Answer 33

three (all from different sites)

Question 34

Give the 4 key investigations that should be carried out for suspected infective endocarditis:

Answer 34

1) blood cultures
2) echocardiography
3) FBC
4) serology for culture negative endocarditis

Question 35

What are 5 intrinsic risk factors for infective endocarditis?

Answer 35

1. Valvular stenosis or regurgitation
2. Hypertrophic cardiomyopathy
3. Structural heart disease with turbulent flow
4. Prosthetic heart valves
5. Previous infection

Question 36

What are 3 extrinsic risk factors?

Answer 36

Intravenous drug use (right-sided endocarditis)
Invasive vascular procedures (e.g. central lines)
Poor oral hygiene/dental infections

Question 37

How long should antibiotics be given for to treat infective endocarditis?

Answer 37

4-6 weeks

Question 38

Give 4 antibiotics given to treat Staphylococcal endocarditis:

Answer 38

1) vancomycin
2) gentamicin
3) flucloxacillin
4) benzylpenicillin