Question

Which method is used to determine the Minimum Inhibitory Concentration (MIC) of an antibiotic?

• A. Disk diffusion method
• B. Broth dilution method
• C. Gram staining
• D. Streak plate method

Hint:

MIC determination → Broth dilution method → Lowest concentration with no growth.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
MIC is the lowest concentration of an antibiotic that prevents the visible growth of a specific bacteria. It is a critical value for determining the effectiveness of a drug.
Step 2: Detailed Explanation:
The Broth Dilution Method involves adding a standard amount of bacteria to tubes (or wells) containing serial dilutions of the antibiotic.
After incubation, the tubes are checked for turbidity (cloudiness), which indicates growth.
The first tube in the series with no visible growth represents the Minimum Inhibitory Concentration.
The Disk Diffusion (Kirby-Bauer) method is qualitative; it measures the size of a "zone of inhibition" but does not provide a specific MIC value.
Gram staining is for identification, and streak plates are for isolation.
Step 3: Final Answer:
The Broth dilution method is used to determine the MIC.