Validation of cefditoren MIC quality control ranges by a multi-laboratory study (2001).

The potency of cefditoren has been well documented to include broad coverage against both Gram-positive and Gram-negative organisms including species causing community-acquired respiratory tract infections. The accuracy of in vitro test results has been questioned due to debate over inconsistencies in quality control (QC) recommendations published by the National Committee for Clinical Laboratory Standards (NCCLS). Previous studies have recommended conflicting and generally broad MIC dilution ranges for several commonly used QC organisms. This study used NCCLS recommended guidelines to re-evaluate the MIC ranges using a seven laboratory M23-A2 design. The results of this multi-laboratory investigation leads to the proposal of the following QC range recommendations for cefditoren: Streptococcus pneumoniae ATCC 49619 (0.016-0.06 microg/mL); Haemophilus influenzae ATCC 49247 (0.06-0.25 microg/mL); Escherichia coli ATCC 25922 (0.12-1 microg/mL); and Staphylococcus aureus ATCC 29213 (0.25-1 microg/mL). These proposed ranges validate those suggested previously for E. coli and the problematic H. influenzae, but a three log(2) dilution range may be sufficient for S. aureus and S. pneumoniae.