Which of the following best defines the minimal inhibitory concentration (MIC)?

What physical principle explains why a paper disk impregnated with an antibiotic produces a circular zone of inhibition on a lawn of bacteria in the Kirby-Bauer test?

You performed a Kirby-Bauer test with three antibiotics: X, Y, and Z. Measured inhibition zones are X = 22 mm, Y = 17 mm, Z = 9 mm. Clinical breakpoints from the reference state: X susceptible ≥ 20 mm; Y susceptible ≥ 18 mm and intermediate 15–17 mm; Z susceptible ≥ 15 mm. How should each antibiotic be classified and how should they be comparatively ranked for empirical selection?

Which procedure describes how to determine the MBC after a broth dilution assay?

A clinical isolate has MIC and MBC determined as follows: MIC = 1 µg/mL; MBC = 32 µg/mL. Another antibiotic shows MIC = 4 µg/mL; MBC = 8 µg/mL. For a severe infection in a patient where bactericidal therapy is preferred, how should these data influence antibiotic selection if achievable serum concentrations for agent A top out at 4 µg/mL and for agent B at 16 µg/mL?