Resistance to aztreonam-avibactam among clinical isolates of Escherichia coli is primarily mediated by altered penicillin-binding protein 3 and impermeability.

This study was conducted to investigate decreased susceptibility (minimum inhibitory concentrations [MICs] 0.25-4 mg/L) and resistance (MICs > 4 mg/L) to aztreonam-avibactam (ATM-AVI). Contemporary non-replicate clinical isolates of carbapenemase-producing Escherichia coli (CP-EC) (n=90) and ESBL-producing E.