In the kirby-Bauer technique, the zone of inhibition is measured and compared to a prepared scale, which correlates the zone of inhibition size with the minimum inhibition concentration (MIC).
NB: Minimal inhibitory concentration (MIC) is the lowest concentration of antimicrobial agent that is required to inhibit in vitro bacterial multiplication under specified conditions. Minimal bactericidal concentration (MBC) is the least concentration of the anti-microbial required producing a sterile culture.
Dilution Sensitivity Tests
Agar dilution tests
Broth dilution tests
Graded amounts of antimcorbial agents are incorporated into liquid or solid bacteriology media. The media are subsequently inoculated with test bacteria and incubated. The end point is taken as that amount of antimicobial agent required to inhibit the growth of the test bacteria (MIC) or to kill the test
bacteria (MBC). Nowadays the
cumbersome, so the advent of microdilution both solution tests has simplified the method and permit a quantitative result to be reported, indicating the amount of a given drug necessary to inhibit or kill the test micro-organism.