INFECTIVE ENDOCARDITIS

Question 1

What is infective endocarditis?

Answer 1

Infection of the endothelial surface of the heart

Question 2

What are some of the predisposing factors to infective endocarditis?

Answer 2

Prosthetic valve insertion
Congenital heart disease - Ventricular septal defect, patent ductus arteriosus
Intravenous drug use
Bicuspid aortic valve
Mitral valve prolapse with mitral regurgitation
Bacteraemia

Question 3

What are the predisposing factors to bacteraemia?

Answer 3

Dental work
Intravenous drug abuse
Invasive procedures - cannulation, catheterisation, surgery
Bowel sepsis

Question 4

What are the most common organisms to cause infective endocarditis?

Answer 4

Streptococcus viridans group - RF, IVDAs, prosthetic valves
Staph aureus - IVDAs
Staph epidermidis - prosthetic heart valves
Enterococci - second most common in developed countries
Gram-negative bacteria - valve surgery
Fungi - IVDAs, valve surgery

Question 5

What are the complications of infective endocarditis?

Answer 5

Local destructive effects - valve incompetence, paravalvular abscesses, myocardial rupture
Heart failure
Thrombo-embolization of infected fragments
Type III autoimmune reaction to organism

Question 6

How quickly after infection would someone with Staph aureus infective endocarditis present?

Answer 6

Quite quickly - S. aureus causes rapid valvular destruction.

Question 7

How quickly after infection would someone with Staph epidermidis infective endocarditis present?

Answer 7

This may take a few months to present - much slower destruction than S. aureus

Question 8

What are the classic symptoms of infective endocarditis?

Answer 8

Fever
Sweats
Anorexia and weight loss
General malaise
Stroke

Question 9

On examination, what cardiac signs might be seen in a patient with infective endocarditis?

Answer 9

Murmur

Signs of heart failure

Question 10

On examination, what peripheral signs might be seen in a patient with infective endocarditis?

Answer 10

Clubbing
Splinter haemorrhages - more than four. Majority caused by trauma
Osler’s nodes - represents peripheral emboli
Janeway lesions - represents peripheral emboli
Roth’s spots - retinal haemorrhages with a pale centre
Splenomegaly

Question 11

What investigations would you order for someone with suspected infective endocarditis?

Answer 11

Blood cultures
Full blood count
ESR
CRP
U+Es
LFTs
Urinalysis
Chest radiograph
Echo

Question 12

How many blood cultures should be taken from a patient with infective endocarditis?

Answer 12

In the non-septic patient where it is preferable to identify the organism before starting anti-biotics, it is best to take three sets of cultures an hour apart.

Question 13

What might a full blood count of someone with infective endocarditis show?

Answer 13

Anaemia of chronic disease
Leucocytosis (neutrophilia)
Thrombocytopenia - DIC

Question 14

Why would you at the U+Es in someone with infective endocarditis?

Answer 14

To check renal function. Can be impaired due to infarction or immune complex-mediated glomerulonephritis. Need constant monitoring due to medication as well.

Question 15

Why might LFTs be deranged in someone with infective endocarditis?

Answer 15

Septic microemboli

Question 16

Why is important to do a urinalysis in a patient with infective endocarditis?

Answer 16

Urine microscopy should be performed to look for casts as seen in glomerularnephritis.

Question 17

What might transthoracic echocardiography show in someone with infective endocarditis?

Answer 17

Valve incompetence

Vegetations

Question 18

What is the more sensitive way to use echocardiography to diagnose vegetations in someone with infective endocarditis?

Answer 18

Transoesophageal

Question 19

What are the major Duke criteria for the diagnosis of infective endocarditis?

Answer 19

Positive blood cultures (two or more with the same organism 12 hours apart)
Evidence of endocardial involvement eg vegetations on echo, abscess or new valvar regurgitation

Question 20

What are the minor Duke criteria for the diagnosis of infective endocarditis?

Answer 20

Fever >38˚
Vascular phenomena eg arterial emboli, mycotic aneurysm, Janeway lesions
Immunological phenomena eg, glomerular nephritis, Roth spots or Osler’s nodes
Predisposition to endocarditis
Additional microbiological evidence not meeting the major criteria

Question 21

What is the likely organism responsible for insidious infective endocarditis in someone with only native valves and what therefore is the antibiotic treatment of choice?

Answer 21

Streptococcus viridans

Benzylpenicillin 2.4g IV 4 hourly (6 weeks)
Gentamicin IV

Question 22

What is the likely organism responsible for acute onset infective endocarditis in someone with only native valves and what therefore is the antibiotic treatment of choice?

Answer 22

Staph aureus

Flucloxacillin IV
Gentamicin IV
Fucidic acid
Cover for MRSA with vancomycin until sensitivities known

Question 23

What is the likely organism responsible for infective endocarditis in someone with a prosthetic valve and what therefore is the antibiotic treatment of choice?

Answer 23

Staph epidermidis

Benzylpenicillin or flucloxacillin IV
Fucidic acid may be added

Question 24

How long does a course of antibiotics for infective endocarditis usually last?

Answer 24

Minimum 6 weeks - can be changed to oral antibiotics after 2 in some cases

Question 25

In addition to antibiotic treatment, how must a patient with infective endocarditis be managed?

Answer 25

Identify source of bacteraemia infection - eg teeth
Daily monitoring for new valvular involvement
Daily urine dipstick
Bi-weekly blood tests for FBC, U+Es, ESR, CRP
Daily ECG
Weekly echo
Surgery is done very rarely and carries a high mortality risk