Zone of inhibition

Definition

The zone of inhibition is the clear region around an antimicrobial agent on an agar plate where bacterial growth has been prevented. It is used to measure the efficacy of the antimicrobial substance.

5 Must Know Facts For Your Next Test

1. A larger zone of inhibition indicates a more effective antimicrobial agent.
2. The diameter of the zone of inhibition is measured in millimeters.
3. It is commonly used in disk diffusion tests, such as the Kirby-Bauer test.
4. Different bacteria and antimicrobials can produce varying sizes of zones of inhibition.
5. Environmental factors like temperature and incubation time can affect the size of the zone.

Review Questions

• What does a larger zone of inhibition indicate?
• How is the size of a zone of inhibition measured?
• Name one test that uses the concept of zone of inhibition.

Related terms

antimicrobial agent: A substance that kills or inhibits the growth of microorganisms.

Kirby-Bauer test: A method used to determine the susceptibility of bacteria to antibiotics using disk diffusion.

agar plate: A Petri dish filled with agar used for culturing microorganisms.