Determination of MIC Quality Control Ranges for Ceftibuten-Avibactam (Fixed 4 μg/mL), a Novel β-Lactam/β-Lactamase Inhibitor Combination

Ceftibuten/ARX-1796 (avibactam prodrug) is a novel oral antibacterial combination in early clinical development for the treatment of complicated urinary tract infections (cUTI) including pyelonephritis. ARX-1796 is the novel avibactam prodrug being combined with ceftibuten for oral dosing that is converted to active avibactam in vivo. A Clinical and Laboratory Standards Institute (CLSI) M23 (2018) tier 2 broth microdilution quality control (QC) study was conducted with ceftibuten-avibactam to establish MIC QC ranges. Ceftibuten-avibactam broth microdilution QC ranges were approved for Escherichia coli ATCC 25922 (0.016/4 to 0.12/4 μg/mL), E. coli NCTC 13353 (0.03/4 to 0.12/4 μg/mL), Klebsiella pneumoniae ATCC 700603 (0.06/4 to 0.25/4 μg/mL), K. pneumoniae ATCC BAA-1705 (0.03/4 to 0.25/4 μg/mL), and K. pneumoniae ATCC BAA-2814 (0.12/4 to 0.5/4 μg/mL) by the CLSI Subcommittee on Antimicrobial Susceptibility Testing in January 2022. Approved ceftibuten-avibactam QC ranges will support future clinical development, device manufacturers, and routine patient care.