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Questions and Answers
What is the purpose of the Kirby-Bauer disk diffusion test?
What is the purpose of the Kirby-Bauer disk diffusion test?
- To determine the size of bacterial pathogens
- To study the growth patterns of bacteria
- To isolate bacterial pathogens from patients
- To test the susceptibility of microbes to antimicrobial drugs (correct)
What is placed on the agar plate during the Kirby-Bauer assay?
What is placed on the agar plate during the Kirby-Bauer assay?
- Filter paper disks impregnated with antibiotics (correct)
- Petri dishes for incubation
- Chemical solutions for staining
- Bacterial pathogen samples
How is antibacterial activity observed in the Kirby-Bauer disk diffusion test?
How is antibacterial activity observed in the Kirby-Bauer disk diffusion test?
- By observing color changes in the agar
- By measuring the growth rate of bacteria
- By noting the presence of a clear circular zone of inhibition (correct)
- By counting the number of filter paper disks
Why does the interpretation of the Kirby-Bauer assay provide only limited information on susceptibility and resistance?
Why does the interpretation of the Kirby-Bauer assay provide only limited information on susceptibility and resistance?
Why can differences in zone sizes not be used to compare drug potencies or efficacies in the Kirby-Bauer test?
Why can differences in zone sizes not be used to compare drug potencies or efficacies in the Kirby-Bauer test?
Flashcards
Kirby-Bauer Test Purpose?
Kirby-Bauer Test Purpose?
Tests microbes' susceptibility to antimicrobials.
Kirby-Bauer: What's on the disk?
Kirby-Bauer: What's on the disk?
Filter paper disks with antibiotics are placed on the agar plate.
Kirby-Bauer: How to observe?
Kirby-Bauer: How to observe?
Antibacterial activity is seen as a clear zone of inhibition.
Kirby-Bauer: Information limits?
Kirby-Bauer: Information limits?
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Kirby-Bauer: Can it compare drugs?
Kirby-Bauer: Can it compare drugs?
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Study Notes
Kirby-Bauer Disk Diffusion Test
- A method for determining the susceptibility of specific microbes to various antimicrobial drugs.
- The test starts with a confluent lawn inoculated with a patient's isolated bacterial pathogen.
Assay Procedure
- Filter paper disks impregnated with known amounts of antibacterial drugs are placed on the agar plate.
- Antibiotic diffuses from the circular disk into the agar and interacts with the growing bacteria.
Zone of Inhibition
- Antibacterial activity is observed as a clear circular zone of inhibition.
- The diameter of the zone of inhibition helps determine the susceptibility or resistance of the bacterial pathogen to a particular drug.
Factors Affecting Zone of Inhibition
- Drug solubility
- Rate of drug diffusion through agar
- Thickness of the agar medium
- Drug concentration impregnated into the disk
Limitations of the Assay
- Lack of standardization of the factors mentioned above.
- Provides only limited information on susceptibility and resistance to the drugs tested.
- Cannot distinguish between bacteriostatic and bactericidal activities.
- Differences in zone sizes cannot be used to compare drug potencies or efficacies.
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