Questions: 18 A clinical microbiologist makes serial dilutions of several antimicrobics in broth, and then incubates each drug dilution series with a standard amount of a patient's isolated pathogen. What is this microbiologist setting up? 5 points Multiple Choice Minimum inhibitory concentration (MIC) Kirby-Bauer test Therapeutic index (TI) Antibiogram E-test

The answer is the first one: Minimum inhibitory concentration (MIC).

Explanation for each option:

1. Minimum inhibitory concentration (MIC): This is the correct answer. The MIC test involves making serial dilutions of an antimicrobial agent in broth and then incubating these dilutions with a standard amount of a pathogen. The goal is to determine the lowest concentration of the drug that inhibits visible growth of the microorganism, which is exactly what the clinical microbiologist is doing in this scenario.

2. Kirby-Bauer test: This is incorrect. The Kirby-Bauer test, also known as the disk diffusion test, involves placing antibiotic-impregnated paper disks on an agar plate inoculated with the pathogen. It measures the zone of inhibition around the disks to determine susceptibility, not serial dilutions in broth.

3. Therapeutic index (TI): This is incorrect. The therapeutic index is a ratio that compares the toxic dose of a drug to its therapeutic dose. It is not determined by serial dilutions in broth.

4. Antibiogram: This is incorrect. An antibiogram is a summary report of the susceptibility of a particular microorganism to a range of antimicrobial agents, typically compiled from multiple MIC or disk diffusion tests, but it is not a test itself.

5. E-test: This is incorrect. The E-test is a method that uses a strip impregnated with a gradient of an antibiotic to determine the MIC on an agar plate, not through serial dilutions in broth.

In summary, the microbiologist is setting up a Minimum inhibitory concentration (MIC) test.