Infective endocarditis

Question 1

what are the causative organisms for endocarditis, and what risk factors are associated with each organism?

Answer 1

staphylococcus aureus

• acute I.E.
• IV drug abusers

staphylococcus epidermidi

• prosthetic valve
• indwelling lines

streptococcus viridans

• poor dental hygiene
• recent dental surgery

streptococcus bovis
- colorectal cancer

Question 2

what conditions can cause endocarditis?

Answer 2

NBTE (non-bacterial thrombotic endocarditis)

SLE
malignancy

Question 3

what diagnostic criteria is used for the diagnosis of I.E.?

Answer 3

Modified dukes criteria

2 major criteria
1 major + 3 minor
5 minor

Question 4

describe the modified dukes criteria.

Answer 4

2 major
1 major + 3 minor
5 minor

major

• positive blood cultures
• evidence on ECHO or new regurgitant murmur

minor

• predisposition i.e. heart condition, IV drug abuse
• fever > 38.5
• immunological phenomenon
• vascular phenomenon
• positive bacterial culture but doesn’t fulfil major criteria

Question 5

what are the signs of endocarditis?

Answer 5

immunological phenomenon

• roth spots
• oslers nodes
• glomerulonephritis
• clubbing

vascular phenomenon

• janeway lesions
• splinter haemorrhages
• pupura/petechiae
• splenomegaly

regurgitant murmur
pyrexia
may have signs of heart failure

Question 6

what investigations would you carry out if you suspected IE?

Answer 6

blood cultures (x3 taken 30 mins apart)
FBC
U&E's
CRP
ESR 
urinalysis 
echocardiogram 
CXR

Question 7

what antibiotic treatment is given for blind therapy in a native valve with IE?

Answer 7

amoxicillin +/- gentamicin

Question 8

what antibiotic treatment is given for blind therapy in a prosthetic valve with IE?

Answer 8

vancomycin + rifampicin + gentamicin

Question 9

what antibiotic treatment is given for I.E. caused by staphylococcus in prosthetic and a native valve?

Answer 9

native = flucloxacillin 
prosthetic = flucloxacillin + rifampicin + gentamicin

Question 10

what are the indications for surgery in IE?

Answer 10

valvular abscess
infections refractory to antibiotic therapy
recurrent arterial emboli after antibiotic treatment
significant valvular regurgitation
cardiac failure refractory to standard treatment

Question 11

what are poor prognostic factors in IE?

Answer 11

prosthetic valve
low complement levels
culture negative endocarditis
staph aureus

Question 12

what are complications of IE?

Answer 12

heart failure (regurgitation = leaflet prolapse. aortic > mitral)
uncontrolled infection = perivalvular abscess 
systemic embolisation of vegetation = PE, stroke, splenic infarction

Question 13

what valve is most commonly affected by IE?

Answer 13

mitral valve