Aztreonam-avibactam: a new combination with activity against multidrug-resistant Klebsiella pneumoniae complex.

Klebsiella pneumoniae complex (KPc) is a group of opportunistic pathogens that pose a serious threat to public health. Multidrug resistance is increasing, and limiting therapeutic options. Aztreonam-avibactam (AZA) is a combination of an established β-lactam with a new β-lactamase inhibitor. The aim of this study was to assess the susceptibility of multidrug-resistant KPc strains to AZA. The study included 52 ESβL-positive strains and 152 carbapenemase-positive KPc strains. The susceptibility to AZA was tested using the gradient strip method. AZA showed high activity against KPc, with MICs ranging from 0.032 to 0.75 μg ml for ESβL-positive strains and from 0.016 to 2 μg ml for carbapenemase-positive strains. The lowest MIC of AZA was obtained for VIM- and ESβL-positive strains at 0.094 μg ml, and MIC for ESβL-positive strains was 0.125 μg ml. AZA demonstrated excellent in vitro activity against the analysed strains, suggesting that this antibiotic may be an effective therapeutic option for treating infections caused by multidrug-resistant KPc strains.