How do microbiologist determine what antibiotics kill certain bacteria?
Some bacteria are just killed by certain drugs, and it is a known fact. For instance, beta-hemolytic strep, like Group A, (which causes strep throat) is ALWAYS sensitive to penicillin. We never have to determine if it will work. Sometimes based on what the organism is, we know what SHOULD work. A good choice for staph is Bactrim. A good choice for Pseudomonas is levofloxacin. Yada, yada. The only way to know FOR SURE is to perform susceptibility testing. Most of the time a microbiologist does what is called a “sensitivity” along with the culture. Sensitivities can be done using an antibiotic disk or with minimum inhibitory concentration (MIC). (There are other ways, but these are the main two.) I will explain MIC in detail. Minimum inhibitory concentration (MIC) is the lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation. Sometimes machines read the result; some readings are done manually. There are standards provid
