A γ-lactam siderophore antibiotic effective against multidrugresistant Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter spp.

Serious infections caused by multidrug-resistant (MDR) organisms (Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii) present a critical need for innovative drug development. Herein, we describe the preclinical evaluation of YU253911, 2, a novel g-lactam siderophore antibiotic with potent antimicrobial activity against MDR Gram-negative pathogens. Penicillin-binding protein (PBP) 3 was shown to be a target of 2 using a binding assay with purified P. aeruginosa PBP3. The specific binding interactions with P. aeruginosa were further characterized with a high-resolution (2.0 A) X-ray structure of the compound's acylation product in P. aeruginosa PBP3. Compound 2 was shown to have a concentration >1 mg/ml at the 6 h time point when administered intravenously or subcutaneously in mice. Employing a meropenem resistant strain of P. aeruginosa, 2 was shown to have dose-dependent efficacy at 50 and 100 mg/kg q6h dosing in a mouse thigh infection model. Lastly, we showed that a novel gamma-lactam and beta-lactamase inhibitor (BLI) combination can effectively lower minimum inhibitory concentrations (MICs) against carbapenem resistant Acinetobacter spp. that demonstrated decreased susceptibility to 2 alone. (C) 2021 Published by Elsevier Masson SAS.

Automated summary

This study demonstrates the preclinical evaluation of a novel γ-lactam siderophore antibiotic, YU253911, showing potent antimicrobial activity against multidrug-resistant Gram-negative pathogens. The compound targets penicillin-binding protein 3 in Pseudomonas aeruginosa and has dose-dependent efficacy in a mouse infection model. Additionally, a combination with a novel beta-lactamase inhibitor was shown to enhance the effectiveness of the antibiotic against carbapenem-resistant Acinetobacter spp.