| Kirby-Bauer (also Bauer-Kirby) disk diffusion antibiotic suseptibility testing applies a defined inoculum (compared to McFarland 0.5 OD standard streaked as a lawn onto a large Mueller-Hinton agar plate (in 3 directions to ensure confluence). Then, using a dispenser such as the one pictured, antibiotic-impregnated disks are placed onto the agar surface. As the bacteria on the lawn grow, they are inhibited to varying degrees by the antibiotic diffusing from the disk. It has been determined that zones of inhibition of a certain diameter (varies for antibiotic and to a lesser extent, bacterial species) correlate with sensitivity or resistance to the antibiotic tested. |
