Quality control guidelines for amoxicillin, amoxicillin-clavulanate, azithromycin, piperacillin-tazobactam, roxithromycin, ticarcillin, ticarcillin-clavulanate, trovafloxacin (CP 99,219), U-100592, and U-100766 for various National Committee for Clinical Laboratory Standards susceptibility testing methods - Results from multicenter trials

Quality control guidelines for standardized antimicrobial susceptibility test methods are critical to the continuing accuracy of the tests. In this report, quality control limits were proposed for 22 organism-antimicrobial combinations with minimum inhibitory concentration (MIC) ranges of three or four log(2) dilution steps. Disk diffusion zone diameter ranges were proposed for azithromycin compared with Neisseria gonorrhoeae ATCC 49226 and ticarcillin with and without clavulanic acid tested against Staphylococcus aureus ATCC 25923. The data from five or six participating laboratories produced greater than or equal to 94.7% of results within proposed MIC limits, and 94.3%-99.0% of zones were found within suggested zone guidelines. These proposed quality control ranges should be validated try in-use results from clinical laboratories.