University of Pennsylvania Medical Center Guidelines for Antibiotic Use




Pictured above is a graph which shows the relationship between the MIC and the size of the zone of inhibition in the Bauer-Kirby test for the drug-A using the bacteria-Q. "R" represents the cutoff for the interpretation of "resistant", and "S" represents the cutoff for the interpretation of "susceptible"

The portion of the curve which is red represents the region where it would be reported that bacteria-Q is resistant to drug-A. Refection of the curve onto the X-axis (dotted red line) show that a zone diameter less than 16 mm (red arrow) is required for "resistant" to be reported out for this bug/drug pair. This correlates approximately with an MIC of >64 micrograms.

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