Susceptibility Testing

Question 1

Characteristic of broth to remember

MIC and how it is determined

Macrodilution vs microdilution

Answer 1

No protein for drug to bind to, all free drug. Highly bound protein drugs will have higher concentration

Minimum INHIBITORY concentration- when does the tube become clear.

Broth volume 1uL vs 100 uL

Question 2

Epsilometer test

Answer 2

Antibiotic strip placed on bacteria streaked plate to test for MIC

Question 3

Name for machine that does MIC testing

Name and mechanism for disc diffusion zone test

Answer 3

Vitek 2

Kriby-Bauer
-S,I,R
-Susceptible
-Susceptibility: dose dependent (higher doses needed)
-Intermediate: Depends on location of bacteria
-Resistant: NO
-Nonsusceptible: For when only susceptible breakpoints designated

Question 4

Best MIC to use

Answer 4

Geometric mean MIC

Question 5

Synergy terms

Answer 5

Synergy- better together by 2 log factor
Antagonism- worse together by 2 log factor
Additivity or indifference- neither

Question 6

Post antibiotic effect

Answer 6

Measures growth after removal of antibiotic