Re-evaluation of quality control guidelines for gatifloxacin and garenoxacin (BMS284756) when susceptibility testing Haemophilus influenzae and Streptococcus pneumoniae

Abstract

An eight laboratory M23-A2 quality control (QC) study was performed for the re-evaluation of gatifloxacin, a new fluoroquinolone, using disk diffusion tests against Streptococcus pneumoniae ATCC 49619. The study also re-evaluated garenoxacin, a novel investigational des-F(6)-quinolone, using disk diffusion tests against S. pneumoniae ATCC 49619 and broth MIC for Hemophilus influenzae ATCC 49247. The gatifloxacin zone diameter results for S. pneumoniae did not indicate a need for QC range modification (26-34 mm; 98.3% of results); however, the garenoxacin zone diameters did demonstrate a need for a minor modification (1 mm; 26-34 mm; 96.3% of reported results). The broth MIC results for H. influenzae showed that 83.1% of the results were at the upper limit of the current range (0.008 μg/ml) published by the National Committee for Clinical Laboratory Standards (NCCLS). The proposed correction could either be 0.002-0.015 μg/ml or 0.004-0.015 μg/ml, each encompassing 100.0% of reported results (prior and current studies). All MIC results for control drugs, levofloxacin and moxifloxacin (disks) or gatifloxacin and clarithromycin (MIC), were within published NCCLS ranges.