How does the antibiotic get from the disk tnto the agar?

The antibiotic in a disk diffusion assay diffuses from the disk into the agar medium due to a concentration gradient. As the antibiotic moves away from the disk, it spreads out into the surrounding agar, creating a zone of inhibition where bacterial growth is prevented. The rate of diffusion depends on factors like the size of the antibiotic molecule and the agar's characteristics. This process allows researchers to assess the antibiotic's effectiveness against specific bacteria by measuring the diameter of the inhibition zone.