In Vitro and In Vivo Development of a β‑Lactam-Metallo-βLactamase Inhibitor: Targeting Carbapenem-Resistant Enterobacterales

β-lactams are the most prescribed class of antibiotics due to their potent, broad-spectrum antimicrobial activities. However, alarming rates of antimicrobial resistance now threaten the clinical relevance of these drugs, especially for the carbapenemresistant Enterobacterales expressing metallo-β-lactamases (MBLs). Antimicrobial agents that specifically target these enzymes to restore the efficacy of last resort β-lactam drugs, that is, carbapenems, are therefore desperately needed. Herein, we present a cyclic zinc chelator covalently attached to a β-lactam scaffold (cephalosporin), that is, BP1. Observations from in vitro assays (with seven MBL expressing bacteria from different geographies) have indicated that BP1 restored the efficacy of meropenem to ≤ 0.5 mg/L, with sterilizing activity occurring from 8 h postinoculation. Furthermore, BP1 was nontoxic against human hepatocarcinoma cells (IC50 > 1000 mg/L) and exhibited a potency of (Kiapp) 24.8 and 97.4 μM against Verona integron-encoded MBL (VIM-2) and New Delhi metallo β-lactamase (NDM-1), respectively. There was no inhibition observed from BP1 with the human zinc-containing enzyme glyoxylase II up to 500 μM. Preliminary molecular docking of BP1 with NDM-1 and VIM-2 sheds light on BP1’s mode of action. In Klebsiella pneumoniae NDM infected mice, BP1 coadministered with meropenem was efficacious in reducing the bacterial load by >3 log10 units’ postinfection. The findings herein propose a favorable therapeutic combination strategy that restores the activity of the carbapenem antibiotic class and complements the few MBL inhibitors under development, with the ultimate goal of curbing antimicrobial resistance.

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Byron K. Peters, Nakita Reddy, Mbongeni Shungube, Letisha Girdhari, Sooraj Baijnath, Sipho Mdanda, Lloyd Chetty, Thandokuhle Ntombela, Thilona Arumugam, Linda A. Bester, Sanil D. Singh, Anil Chuturgoon, Per I. Arvidsson, Glenn E. M. Maguire, Hendrik G. Kruger, Tricia Naicker, and Thavendran Govender ACS Infectious Diseases 2023 9 (3), 486-496 DOI: 10.1021/acsinfecdis.2c0048

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https://uzspace.unizulu.ac.za/handle/10530/2440

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