Antibiotic prophylaxis

Question 1

What are the broad indications for endocarditis prophylaxis?

Answer 1

To benefit patients should:
1. have cardiac condition associated with an increased risk of developing IE and the highest risk of adverse outcomes from endocarditis

2. undergoing a procedure associated with a high risk of a bacteraemia that is associated with endocarditis

Question 2

What cardiac conditions put patients at risk of endocarditis?

Answer 2

prosthetic valve or other material such as annuloplasty
previous IE
congenital heart disease that involves: unrepaired cyanotic defects or repaired defects or repaired defects that have prosthetic material that cannot endothelialise
rheumatic heart disease

Question 3

Which procedures require prophylaxis in susceptible individuals?

Answer 3

Dental procedures involving perforation of oral mucosa
Procedures involving infected skin
Tonsillectomy
Genitourinary procedures where surgical antibiotic prophylaxis is required

Question 4

Endocarditis prophylaxis in dental procedures

Answer 4

amox 2g PO, 60 minutes prior

Question 5

What are the MICs that dictate vancomycin:
sensitive
intermediate
resistant

Answer 5

sensitive <2mcg/mL
intermediate 4-8
resistant >16

Question 6

What is VISA and what is the mechanism

Answer 6

VISA = vancomycin-intermediate S. aureus
mediated by thickened cell wall
usually develop from MRSA strains that have prolonged exposure to Vancomycin

Question 7

What is VRSA and what is the mechanism

Answer 7

VRSA = vancomycin resistant S. aureus
due to van gene cluster which results in change in the cell wall terminal peptide (D-ala-D-lac) instead of (D-ala-D-ala)

Question 8

What antibiotic options are available for those with VRSA?

Answer 8

Ceftaroline
Linezolid

Question 9

What defines MSSA vs MRSA

Answer 9

Oxacillin MIC > 4 is resistant
MIC < 2 is sensitive

Question 10

What gene confers methicillin resistance?

Answer 10

mec