Reproducibility of broth microdilution and disk diffusion susceptibility tests of nine antimicrobial agents against Streptococcus pneumonia ATCC 49619

Collaborative studies documented the reproducibility of broth microdilution susceptibility tests of Streptococcus pneumoniae against nine antimicrobial agents and of disk diffusion tests with six of those drugs. Replicate tests of Streptococcus pneumoniae ATCC 49619 in five different laboratories led to the following provisional quality control limits: cefdinir-0.03 to 0.25 μg/ml and 26 to 31 mm; cefetamet-0.5 to 2 μg/ml and 20 to 25 mm; ciprofloxacin-0.25 to 1 μg/ml and 20 to 26 mm; clinafloxacin- 0.03 to 0.125 μg/ml and 28 to 34 mm; grepafloxacin-0.06 to 0.5 μg/ml and 21 to 28 mm; PD131628-0.125 to 0.5 μg/ml and 24 to 29 mm; clindamycin-0.03 to 0.12 μg/ml; cefpodoxime-0.03 to 0.12 μg/ml; and trospectomycin-1 to 4 μg/ml (disk tests were not evaluated for the latter three drugs).