Determination of MIC Quality Control Ranges for the Novel Gyrase Inhibitor Zoliflodacin

This report describes the results of two different, multilaboratory quality control (QC) studies that were used to establish QC ranges for the novel gyrase inhibitor zoliflodacin against the ATCC strains recommended by the Clinical and Laboratory Standards Institute (CLSI). Following the completion of an eight-laboratory, CLSI document M23-defined tier 2 study, the agar dilution MIC QC range for zoliflodacin against the Neisseria gonorrhoeae QC strain ATCC 49226 was defined as 0.06 to 0.5 μg/ml and was approved by the CLSI Subcommittee on Antimicrobial Susceptibility Testing. This QC range will be used for in vitro susceptibility testing of zoliflodacin during phase 3 human clinical trials and surveillance studies, and eventually it will be implemented in clinical labs. In a separate study, broth microdilution MIC quality control ranges for zoliflodacin against additional QC strains were determined to be 0.12 to 0.5 μg/ml for Staphylococcus aureus ATCC 29213, 0.25 to 2 μg/ml for Enterococcus faecalis ATCC 29212, 1 to 4 μg/ml for Escherichia coli ATCC 25922, 0.12 to 0.5 μg/ml for Streptococcus pneumoniae ATCC 49619, and 0.12 to 1 μg/ml for Haemophilus influenzae ATCC 49247. These MIC QC ranges were also approved by CLSI for use in future in vitro susceptibility testing studies against organisms other than N. gonorrhoeae .