Interpretation of susceptibility testing of ceftriaxone.

Susceptibility of a variety of bacterial isolates to ceftriaxone was determined by Kirby-Bauer assays using 30 micrograms ceftriaxone disks and by microdilution (MIC) assays using standard procedures. The relation between zones of inhibition and MICs was expressed by the following regression equation: zone diameter = 22.98-2.