Microbiology 26 - Infective endocarditis (path guide not lectures)

Question 1

Recall some risk factors for infective endocarditis

Answer 1

Dental PMH
RhF
Congenital heart disease
Valve replacement
Long term lines

Question 2

Recall some signs of SUBACUTE infective endocarditis that wouldn’t be seen in its acute form

Answer 2

Embolic phenomena:
Janeway lesions
Splinter haemorrhages
Splenomegaly

Immune phenomena:
Roth spots
Osler’s Nodes
Haematuria

Question 3

Recall the major criteria in the Duke Classificiation for infective endocarditis

Answer 3

• Positive blood culture growing typical organisms (>2x cultures >12hrs apart)
• New regurgitant murmur or evidence of vegetation on echo

Question 4

What is the most likely pathogen in subacute infective endocarditis?

Answer 4

Strep viridians or staph epididermis

Question 5

What is the most likely pathogen in acute infective endocarditis with a prosthetic heart valve?

Answer 5

CoNS (Coagulase negative Staph: S.epidermidis, S.saprophyticus)

Question 6

Which valve is most likely to be affected in infective endocarditis in an IV drug user?

Answer 6

Tricuspid in 50%

Question 7

What is the most important investigation to order in susected infective endocarditis?

Answer 7

3 blood cultures taken from 3 DIFFERENT sites

Question 8

Most common causes of acute infective endocarditis

Answer 8

Strep pyogenes (GAS)
Staph aureus (IVDU)
CoNS (S.epidermidis, S.saprophyticus) in those with prosthetic valves

Question 9

Duke’s criteria to diagnose infective endocarditis

Answer 9

2 major (>2+ve cultures 12hrs apart, new murmur/vegetation on echo)
or
1 major 3 minor
or
5 minor
- Risk factors- IVDU, long term lines, poor dentition
- Fever >38°
- Embolic phenomena (janeway lesions, splinter haemorrhages)
- Immune phenomena (osler nodes, roth spots, haematuria)
- Positive blood cultures not meeting major criteria