Final answer:
The MIC or minimal inhibitory concentration is the lowest concentration of an antimicrobial drug that inhibits visible growth of a microorganism. It can be determined through various methods, including the Etest. The approximate MIC can be obtained from MIC strip test results.
Step-by-step explanation:
The MIC or minimal inhibitory concentration is the lowest concentration of an antimicrobial drug that inhibits visible growth of a microorganism. It is determined through various methods, such as the Kirby-Bauer disk diffusion test, dilution tests, and the Etest. In the Etest, plastic strips containing a gradient of an antibacterial are placed on an agar plate with bacterial cells. The MIC is then determined by the intersection of the elliptical zone of inhibition with the drug gradient on the strip.
The approximate MIC for a specific drug against a specific organism can be obtained from MIC strip test results. For example, in Figure 14.21, the MIC of vancomycin against Staphylococcus aureus is approximately 1.5 µg/mL.
It is important to note that the MIC indicates the concentration needed to inhibit visible growth, but it does not provide information on bactericidal activity or allow for direct comparison of drug potencies.