Impact of Acquired Broad-Spectrum β-Lactamases on Susceptibility to Cefiderocol and Newly Developed β-Lactam/β-Lactamase Inhibitor Combinations in Escherichia coli and Pseudomonas aeruginosa

The ability of broad-spectrum β-lactamases to reduce the susceptibility to ceftazidime-avibactam (CZA), ceftolozane-tazobactam (C/T), imipenem-relebactam, meropenem-vaborbactam, aztreonam-avibactam (AZA), and cefiderocol (FDC) was evaluated both in Pseudomonas aeruginosa and in Escherichia coli using isogenic backgrounds. Although metallo-β-lactamases conferred resistance in most cases, except for AZA, several clavulanic-acid-inhibited extended-spectrum β-lactamases (PER, BEL, SHV) had a significant impact on the susceptibility to CZA, C/T, and FDC.