Final answer:
The diffusion bioassay determines the concentration of antimicrobial in a fluid, using diffusion principles similar to those in the Kirby-Bauer test, but it does not provide MIC or MBC values.
Step-by-step explanation:
The diffusion bioassay is designed to determine the concentration of antimicrobial in a fluid. It does not directly provide the concentration of antimicrobial necessary to kill or inhibit the growth of a bacteria, which is what the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) are used for. These are determined through dilution tests such as the macrobroth or tube dilution assay. The Kirby-Bauer test, on the other hand, is a disk diffusion method used to determine the effectiveness of antimicrobial drugs against specific bacteria by observing the zone of inhibition around disks impregnated with the drugs. Although the principle of diffusion is used in both Kirby-Bauer test and diffusion bioassays, the Kirby-Bauer test is standardized to evaluate susceptibility, not to determine drug concentration.