AST testing

Question 1

What organisms can be tested using Standard Kirby Bauer method?

Answer 1

rapidly growing non-fastidious aerobes and facultative anaerobes

Question 2

MH plates are stored in plastic bags to minimize moisture loss. If plates are allowed to become too dry, what can be the consequence?

Answer 2

falsely resistant results can occur

Question 3

The bacterial inoculum equivalent to a # 0.5 McFarland Standard

Answer 3

1.5 X 10^8 CFU/mL

Question 4

In AST of an organism, the zone size achieved in the disk diffusion method and the MIC’s achieved in a broth dilution procedure are:

Answer 4

are inversely related, the smaller the zone size, the higher the MIC

Question 5

Antimicrobial discs used for susceptibility testing are stored in a closed container with a dessicant and are

Answer 5

allowed to warm to room temperature before use

Question 6

When troubleshooting a failed AST QC, the first thing we look for are the “obvious causes of error” such as

Answer 6

disk error, inoculum error, and incubation

Question 7

What is Haemophilus Test Medium composed of

Answer 7

HTM is Mueller Hinton agar with added hematin, NAD and yeast extract