Let's  say you wish to determine the minimum inhibitory concentration( MIC) of an antibiotic on a bacterium. You decide to test 3 concentrations (10 µg/ml, 1 µg/ml and 0.1 µg/ml). Each of these tubes has growth media inoculated with a standard concentration of bacteria and the respective antibiotic concentration.

The tubes are allowed to incubate overnight. Broth tubes that appear turbid are indicative of bacterial growth while tubes that remain clear indicate no growth. The MIC of the antibiotic is the lowest concentration that does NOT show growth.

After incubating the tubes overnight, you observe the tubes in Figure 2:

From this example, Tube C, (with 0.1 ug/ml of antibiotic) did not inhibit bacterial growth. Tubes A and B, on the other hand, did inhibit growth. Tube B has the minimum inhibitory concentration because B is the lowest concentration of the antibiotic that inhibited cell growth. Therefore, the MIC for this bacterium is 1 µg/ml.

Please, go through this link

http://microchemlab.com/test/minimum-inhibitory-concentration-test-mic-0

Follow the above answers. In addition to the above answers, the test broth should be Muller Hinton. Also follow CLSI guidlines to understand in details.

https://www.boundless.com/microbiology/textbooks/boundless-microbiology-textbook/antimicrobial-drugs-13/measuring-drug-susceptibility-157/minimal-inhibitory-concentration-mic-790-10813/

Let me explain you in simple way. Firstly inoculate the test organism for over night incubation. After incubation take 100 ul from the overnight culture and dilute with 900 ul of fresh MHA broth and final volume will be 1 ml. Then in the microtitre plate leave first well empty in the column and next wells in the column add 100 ul of MHA broth. Take 10 mg of test compound and dilute in the 1 ml of DMSO. Then 512 ul (1 ug/ ul) from that and add it into the 1 ml of culture. From that you take 200 ul and add it into first well which you left as empty. Then you take 100 ul from that you do serial dilution to other wells. Use proper control without addition of test compound and with DMSO alone with cells as another control.

Thank you

It is simple like a serial dilution methods...

there are two different methods adopted to explain MIC of test compound

1. Macro 2.Micro dilution method

In macro dilution method, performed with test tubes and it needs larger volume 1-5ml

where as micro dilution was performed smaller volume, i.e with 96well plate..

A least concentration of drug to inhibit the growth of an organism that means that well or a test tube must be clear in nature...

During antibacterial study using broth dilution method, MIC can be calculated by the formula: -

MIC= (Lowest conc. inhibit growth + Highest conc. allow growth)/2

For example, you prepared a 20 µg/ml stock solution. Let’s say through serial dilution you got four concentrations as 20 µg/ml (stock), 10 µg/ml (1st dilution), 5 µg/ml (2nd dilution), and 2.5 µg/ml (3rd dilution). Transfer them to four different test tubes (as T1, T2, T3, and T4) respectively. Each tube contains MHB media, inoculated with a standard number of bacteria then incubate overnight. After incubation assume tubes (T3 & T4) appear turbid while tubes (T1 & T2) remain clear indicate no growth. The MIC of the antibacterial agent is calculated as

(10 µg/ml + 5 µg/ml)/2 =7.5 µg/ml