In vitro antimicrobial susceptibility testing using 30 microG and 75 microG U63196-E (cefpimizole AC-1370) disks.

U63196-E, a new cephalosporin, was evaluated for its antimicrobial spectrum and its application to standardized in vitro susceptibility test methods. The proposed criteria for the 75-micrograms U63196-E disk are greater than or equal to 18 mm (less than or equal to 16 micrograms/ml) = susceptible and less than or equal to 14 mm (greater than 32 micrograms/ml) = resistant. These limits are preferred to the 30 micrograms disk and produce only 4.2% major and very major interpretive errors. Previously published interpretive criteria for the 75 micrograms cefoperazone disk were confirmed.