Merck & Co. Inc. has reported the development of a novel monobactam for use in combination with its class A/C β-lactamase inhibitor (BIL) relebactam (MK-7655) in order to achieve the broadest activity against multidrug-resistant (MDR) gram-negative pathogens that express a variety of β-lactamases. The in vitro efficacy of the combination of the monobactam – MSD-045934942 – against a panel of MDR and non-MDR gram-negative bacteria was evaluated using in vitro broth microdilution testing.