This Spring 2024 semester, I am on sabbatical at Loyola Marymount University (Lum Lab) learning how to incorporate microbiology techniques into my Organic Chemistry classes.  Here is an example showing how the Kirby-Bauer assay is used to determine whether a particular antibiotic will be effective against clearing a particular type of infection.  In the Kirby-Bauer Test, the drug compound diffuses out of the disc and into the surrounding media, interacting with the bacteria that is growing on the media.  You can measure the diameter of the zone of inhibition to get a sense of the effectiveness of the antibacterial properties of each compound.  I used six standard discs here and tested them against a lawn of E. coli incubated overnight at 37 oC.  Using the reference table, which antibiotics is this E. coli bacteria susceptible to?  Which antibiotics is this E. coli resistant to?  E. coli happens to be a Gram-negative bacterium.  When I tried this experiment with S. epidermidis (a common Gram-positive bacteria found on the skin), I found that S. epidermidis was susceptible to ALL six of these antibiotics!  The point here is that different antibiotics are good/bad against different strains of bacteria.  Penicillin, which apparently has no effect on E. coli is terrific against S. epidermidis.  It makes sense why there are so many different antibiotics out there (because there are so many different strains of bacteria!).  Not to mention, that a particular strain of bacteria can rapidly develop resistance to an antibiotic too so that an antibiotic that works today on that strain might not work later on an evolved descendant of that same bacteria!  We need scientists to think about and work on problems like these.  Consider joining the Science 10 Drug Discovery Lab course to get hands-on experience and learn more!