Zones of inhibition

Definition

Zones of inhibition are clear areas surrounding an antimicrobial agent on an agar plate where microbial growth is prevented. They are used to measure the effectiveness of antiseptics and disinfectants against specific microorganisms.

5 Must Know Facts For Your Next Test

1. Zones of inhibition are measured in millimeters from the edge of the disk to the edge of the clear area.
2. The size of the zone of inhibition indicates the potency of the antimicrobial agent.
3. Larger zones generally mean more effective antimicrobial action, but factors such as diffusion rate and inoculum size can affect results.
4. Standardized testing methods like the Kirby-Bauer disk diffusion test are commonly used to create and measure zones of inhibition.
5. Interpretation charts are used to determine whether a microorganism is susceptible, intermediate, or resistant based on zone size.

Related terms

Kirby-Bauer Test: A standardized method for assessing antibiotic susceptibility using disk diffusion.

Antibiogram: A report that shows the susceptibility of bacteria to various antimicrobial agents.

Minimum Inhibitory Concentration (MIC):

The lowest concentration of an antimicrobial agent that inhibits visible growth of a microorganism.