Infective Endocarditis

Question 1

Define infective endocarditis

Answer 1

Infection involving the endocardial surface of the heart (valves, chordae tendineae, septal
defects, mural endocardium)

Question 2

What are the causes/ risk factors of infective endocarditis?

Answer 2

Endothelial damage -> platelet and fibrin deposition -> bacterial colonisation and vegetation
• Streptococcus viridans – oral commensal; dentition; damaged valves
• Staphylococcus aureus – IVDU; healthy heart
• Enterococcus
• Staphylococcus epidermidis – prosthetic heart valves

Question 3

What are the symptoms of infective endocarditis?

Answer 3

• Fever
• Night sweats
• Malaise
• Fatigue
• Weight loss
• Anorexia
• Myalgia
• Headache (?septic emboli)
• Weakness (?septic emboli)

Question 4

What are the signs of infective endocarditis?

Answer 4

• Splinter haemorrhages
• Clubbing
• Osler nodes
• Janeway lesions
• Roth spots
• New cardiac murmur

Question 5

What is Duke’s criteria for diagnosing infective endocarditis?

Answer 5

Major Criteria – BE
Blood culture +ve
• Typical micro-organisms in 2 seperate cultures or
• Persistently +ve blood cultures drawn 12 hours apart or
• Single +ve blood culture for Coxiella burnetti
Endocardial involvement
• +ve echocardiogram (vegetation, abscess or valve dehiscence) or
• New valvular regurgitation

Minor criteria – FIVE PM
Fever > 38 degrees celsius
Immunologic phenomena
• Glomerulonephritis
• Osler’s nodes
• Roth’s spots
• Rheumatoid factor
Vascular phenomena
• Major arterial emboli
• Septic pulmonary infarcts
• Mycotic aneurysm
• Intracranial haemorrhage
• Conjunctival haemorrhage
• Janeway lesions
Echocardiography findings (suggestive but not definitive)
Predisposition (heart condition or IV drug user)
Microbiological evidence (+ve blood culture not meeting major criteria)
Definitive Diagnosis
• 2 Major or
• 3 Minor + 1 Major or
• 5 Minor