Bacterial antimicrobial resistance (AMR) is a key global public health challenge. Estimates based on 2019 data 1 identify 1.3m deaths worldwide as directly attributable to AMR, with AMR a contributing factor to a further 3.7m. A previous study projected an annual total of 10m deaths by 2050 in the absence of effective interventions. Two species of Enterobacterales, Escherichia coli and Klebsiella pneumoniae, are respectively the first and third most common pathogens responsible for AMRassociated deaths. Strains of these organisms resistant to carbapenems or extended-spectrum oxyimino cephalosporins are considered by the World Health Organization to be critical priority pathogens for antimicrobial research and development due to the weakness of the antibacterial discovery pipeline for these and other multiresistant Gram-negative bacteria.