Tests for susceptibility of streptococcus pneumoniae to cefdinir: Proposed interpretive criteria and quality control parameters for broth microdilution and disc diffusion methods

Proposed quality control (QC) parameters for susceptibility testing of Streptococcus pneumoniae to cefdinir were developed following the procedure recommended by the National Committee for Clinical Laboratory Standards. The proposed QC MIC range for microdilution susceptibility testing of S. pneumoniae ATCC 49619 is 0.06-0.25 mg/L. The proposed QC limits for inhibitory zone diameters of S. pneumoniae ATCC 49619 around 5 μg cefdinir disks is 26-31 mm. We recommend the following for tentative interpretive criteria for determining the susceptibility of S. pneumoniae to cefdinir: susceptible, MIC ≥0.5 mg/L or inhibition zone diameter ≥23 mm; intermediate, MIC 1.0 mg/L or inhibition zone, 20-22 mm; resistant, MIC ≥2.0 mg/L or inhibition zone diameter, ≤ 19 mm for broth microdilution and disc diffusion tests, respectively.