Answer :
The primary purpose of the Kirby-Bauer disk diffusion test is to test the effectiveness of different antibiotics on a bacterial strain. Therefore, the correct answer is C) To test the effectiveness of different antibiotics on a bacterial strain.
The Kirby-Bauer disk diffusion test, also known as the agar diffusion test, is a method used to evaluate whether certain antibiotics can effectively inhibit the growth of specific bacteria. Here’s how the test generally works:
Preparation of Culture Medium: A Petri dish is filled with agar (a gel-like substance derived from seaweed) which acts as a growth medium for bacteria.
Inoculation of Bacteria: A sample of bacteria is evenly spread across the agar surface to ensure consistent growth during testing.
Application of Antibiotic Disks: Small paper disks impregnated with known concentrations of different antibiotics are placed on the surface of the agar.
Incubation: The Petri dish is then incubated at a specific temperature to allow the bacteria to grow. During this period, antibiotics diffuse from the disks into the agar.
Observation of Results: After incubation, the Petri dish is examined for zones of inhibition - clear areas around the disks where bacteria have not grown. The size of these zones indicates the effectiveness of the antibiotic; larger zones suggest more effective inhibition of bacterial growth.
This test is crucial in clinical settings to help determine which antibiotics a particular bacterial infection is susceptible to, thus guiding proper treatment choices. Understanding which antibiotics are effective helps in combating antibiotic resistance by avoiding the use of ineffective treatments.
