What is the zone of inhibition?

The zone of inhibition is a circular area around an antimicrobial agent or antibiotic disk on an agar plate where no bacterial growth is observed. It is a measure of the effectiveness of the antimicrobial agent in inhibiting the growth of bacteria.

The size of the zone of inhibition can vary depending on the antimicrobial agent being tested, the concentration of the agent, and the susceptibility of the bacteria being tested. A larger zone of inhibition indicates greater effectiveness of the antimicrobial agent.

The zone of inhibition is measured in millimeters using a ruler or calipers and can help determine the sensitivity of bacteria to specific antibiotics. It is an important tool in determining the appropriate treatment for bacterial infections and in monitoring the development of antibiotic resistance.

Interpreting the results of the zone of inhibition test requires knowledge of the specific bacteria being tested and the breakpoints established by the Clinical and Laboratory Standards Institute (CLSI) or other standard-setting organizations.