1. Susceptibility Testing
Kirby-Bauer by Jessica Davies

2. What is it??
It determines the sensitivity or resistance of pathogenic aerobic and facultative anaerobic bacteria to various antimicrobial compounds
Helps assist a physician in selecting treatment options for his or her patients 

3. How is it performed?? 1. Sample colony with a straight wire.
2.      Prepare a suspension in 2.5 ml normal saline.
3.      Inoculate a pre-dried agar plate.
4.      Distribute the inoculum by rocking.
5.      Remove excess inoculum.
6.      Dry the plate at room temperature.
7.      Load the plate with antibiotic discs.
8.      Incubate for 18 hours.
9.      Measure the annular radii.
10.   Interpret zone sizes.

4. How do you interprete it??
Simplest explanation is the larger the area of bacteria free space around the antibiotic discs, the less resistance the bug has against that antibiotic. Therefore it is the better antibiotic to use for treatment.