University of Pennsylvania Medical Center Guidelines for Antibiotic Use


Measurement of MIC

The minimum inhibitory concentration or MIC is defined as the minimum concentration of antibiotic which will inhibit the growth of the isolated microorganism . There are many ways to measure the MIC, including:

This figure shows a schematic of the broth dilution test. Bacteria are inoculated into tubes containing culture broth and varying concentrations of the antibiotic to be tested. The tubes are incubated to allow bacterial growth. The MIC is read as the lowest concentration of antibiotic which inhibited bacterial growth. In the above example, the MIC would be 8 micrograms/ml. The interpretation of this MIC depends on the organism/antibiotic pair being tested, and is made following standard NCCLS guidelines.

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