Interpretive criteria and quality control guidelines for Neisseria gonorrhoeae susceptibility test standardization for cefotetan

Abstract

Cefotetan was tested in a multilaboratory study to standardize susceptibility testing criteria and quality control guidelines for Neisseria gonorrhoeae. Cefotetan was most active against penicillinase-producing and penicillin-susceptible strains (MIC for 50% of strains tested, 0.5 ,ug/ml) and was least active against the chromosomally resistant isolates (MIC for 50% of strains tested, 2 ,ug/ml). The recommended 30-,ug disk cefotetan interpretive criteria were as follows: susceptible at .26 mm (c2 rig/ml), intermediate at 20 to 25 mm (4 ,ug/ml), and resistant at l19 mm (.8 ,Lg/ml). Quality control guidelines for agar dilution and disk diffusion tests were established by using numerous GC agar lots, three cefotetan 30-,ug disk lots, two quality control organisms, and a volume of tests consistent with National Committee for Clinical Laboratory Standards M23-T guidelines.