Which term denotes a disk diffusion test used to determine antibiotic susceptibility?

Which term denotes a disk diffusion test used to determine antibiotic susceptibility?

• A. Bacteriostatic
• B. Minimum Inhibitory Concentration (MIC)
• C. Kirby-Bauer Test
• D. Bactericidal

Answer: (C)

The disk diffusion method used to determine antibiotic susceptibility is the Kirby-Bauer test. In this approach, antibiotic-impregnated disks are placed on an agar plate that has been inoculated with the bacterium being tested. The antibiotics diffuse into the surrounding agar, and if the organism is susceptible, a clear zone of inhibited growth forms around the disk. The size of each inhibition zone is measured and compared to standardized criteria to categorize the bacterium as susceptible, intermediate, or resistant. This is different from the minimum inhibitory concentration, which identifies the smallest amount of antibiotic that stops growth in liquid culture, or from terms that describe the effect of the antibiotic on bacteria (bacteriostatic vs bactericidal) rather than a testing method.

The disk diffusion method used to determine antibiotic susceptibility is the Kirby-Bauer test. In this approach, antibiotic-impregnated disks are placed on an agar plate that has been inoculated with the bacterium being tested. The antibiotics diffuse into the surrounding agar, and if the organism is susceptible, a clear zone of inhibited growth forms around the disk. The size of each inhibition zone is measured and compared to standardized criteria to categorize the bacterium as susceptible, intermediate, or resistant. This is different from the minimum inhibitory concentration, which identifies the smallest amount of antibiotic that stops growth in liquid culture, or from terms that describe the effect of the antibiotic on bacteria (bacteriostatic vs bactericidal) rather than a testing method.