Infective endocarditis

Question 1

Define infective endocarditis

Answer 1

Infection of the intracardiac endocardial structures (mainly heart valves)

Question 2

Most common causative organisms of infective endocarditis

3

Answer 2

Streptococci (40%) - mainly a haemolytic S. viridans & S. bovis

Staphylococci (35%) - S. aureus & S. epidermis

Enterococci (20%) - usually E. faecalis

Question 3

Other causative organisms of infective endocarditis

5

Answer 3

haemophilus
actinobacillus
cardiobacterium
coxiella burnetti
histoplasma (fungal)

Question 4

Pathophysiology of infective endocarditis

4

Answer 4

Vegetations form when organisms deposit on heart valves during a period of bacteraemia
Vegetations made up of platelets, fibrin & infective organisms
Destroy valve leaflets, invade myocardium or aortic wall leading to abscess cavities
Activation of immune system can lead to formation of immune complexes —> vasculitis, glomerulonephritis, arthritis

Question 5

Risk factors for infective endocarditis

4

Answer 5

Abnormal valves (e.g. congenital, calcification, rheumatic heart disease)
Prosthetic heart valves
Turbulent blood flow (e.g. patent ductus arteriosus
Recent dental work/poor dental hygiene (source of S. viridans)

Question 6

Epidemiology of infective endocarditis

prevalence

Answer 6

UK incidence: 16-22/million per year

Question 7

Presenting symptoms of infective endocarditis

6

Answer 7

Fever with sweats/chills/rigors (may be relapsing/remitting)
Malaise
Arthralgia
Myalgia 
Confusion
Skin lesions

Question 8

Signs of infective endocarditis on physical examination

12

Answer 8

Pyrexia
Tachycardia
Signs of anaemia
Clubbing
New regurgitant murmur or muffled heart sounds
Frequency of heart murmurs
mitral > aortic > tricuspid > pulmonary
Splenomegaly 
Vasculitic lesions
Petechiae on pharyngeal & conjunctival mucosa
Janeway lesions 
Osler’s nodes
Splinter haemorrhages

Question 9

Investigations for infective endocarditis

5 types

Answer 9

Bloods
Urinalysis
Blood culture
Echocardiography
Duke's classification

Question 10

Investigations for infective endocarditis - bloods

4

Answer 10

FBC - high neutrophils, normocytic anaemia
High ESR/CRP
U&Es
May are rheumatoid factor positive

Question 11

Investigations for infective endocarditis - urinalysis

2

Answer 11

Microscopic haematuria

Proteinuria

Question 12

Investigations for infective endocarditis - blood culture

Answer 12

Microscopy & sensitivities also

Question 13

Investigations for infective endocarditis - echocardiography

Answer 13

Transthoracic or transoesophageal (produces better image)

Question 14

Investigations for infective endocarditis - Duke’s classification

Answer 14

Method of diagnosing infective endocarditis based on findings of investigations & symptoms/signs

Question 15

Management of infective endocarditis

7

Answer 15

Antibiotics for 4-6 weeks
On clinical suspicion => EMPIRICAL TREATMENT
benzylpenicillin
gentamicin
Streptococci: same as above
Staphylococci 
flucloxacillin/vancomycin
gentamicin
Enterococci
ampicillin
gentamicin
Culture negative
vancomycin
gentamicin
SURGERY - urgent valve replacement may be needed if poor response to antibiotics

Question 16

Complications of infective endocarditis

7

Answer 16

Valve incompetence
Intracardiac fistulae or abscesses
Aneurysm
Heart failure 
Renal failure
Glomerulonephritis 
Arterial emboli from vegetations shooting to brain, kidneys, lungs & spleen

Question 17

Prognosis of infective endocarditis

2

Answer 17

FATAL if untreated

15-30% mortality even with treatment