Agar Dilution (MIC) Susceptibility Test Method

In this video I'll describe the process of determining antimicrobial minimum inhibitory concentrations (MICs) using the agar dilution method. Agar dilution has a lot of advantages (low reagent costs and ability to customize) but is quite laborious to perform; preparation of the media is the most time consuming step.

Principle of the test: 0:06
Calculating antibiotic powder mass and solution volume: 3:48
Demonstration of media preparation: 7:36
Testing isolates: 8:55
Reading the plates: 10:35

The tests shown in this video were done in accordance with the Clinical and Laboratory Standards Institute (CLSI) guidelines. The CLSI now provides a set of resources free of charge on their webiste: https://clsi.org/all-free-resources/

The European Committee on Antimicrobial Susceptibility Testing (EUCAST) provides all of their guidelines free of charge on their website. Particularly relevant to this technique are the EUCAST guidelines for preparing media: https://www.eucast.org/ast_of_bacteri... and those describing the recommended quality control organisms: https://www.eucast.org/ast_of_bacteri...