What is a zone of inhibition?

A zone of inhibition is an area on a culture plate where bacteria are unable to grow due to the presence of an antimicrobial agent such as antibiotics, disinfectants, or antiseptics. It is a clear area surrounding the disk or well that contains the antimicrobial agent, indicating that the bacteria are sensitive to the substance and cannot grow in its presence.

The size of the zone of inhibition can vary depending on the potency of the antimicrobial agent, the susceptibility of the bacteria, and the diffusion rate of the agent through the agar. Larger zones of inhibition typically indicate a more effective antimicrobial agent or a more susceptible strain of bacteria.

Zone of inhibition testing is commonly used in laboratories to determine the effectiveness of antimicrobial agents against specific strains of bacteria. It is an important tool in antimicrobial susceptibility testing and can help guide the selection of appropriate treatments for bacterial infections.