Journal of Antimicrobial Chemotherapy
Abstract: Objectives: Class C β-lactamases are prevalent among Enterobacteriaceae; however, these enzymes are resistant to inactivation by commercially available β-lactamase inhibitors. In order to find novel scaffolds to inhibit class C β-lactamases, the comparative efficacy of monocyclic β-lactam antibiotics (aztreonam and the siderophore monosulfactam BAL30072), the bridged monobactam β-lactamase inhibitor BAL29880, and carbapenems (imipenem, meropenem, doripenem and ertapenem) were tested in kinetic assays against FOX-4, a plasmid-mediated class C β-lactamase (pmAmpC). Methods: The FOX-4 β-lactamase was purified. Steady-state kinetics, electrospray ionization mass spectrometry (ESI-MS) and ultraviolet difference (UVD) spectroscopy were conducted using the β-lactam scaffolds described. Results: The Ki values for the monocyclic β-lactams against FOX-4 β-lactamase were 0.04 ± 0.01 μM (aztreonam) and 0.66 ± 0.03 μM (BAL30072), and the Ki value for the bridged monobactam BAL29880 was 8.9 ± 0.5 μM. For carbapenems, the Ki values ranged from 0.27 ± 0.05 μM (ertapenem) to 2.3 ± 0.3 μM (imipenem). ESI-MS demonstrated the formation of stable covalent adducts when the monocyclic β-lactams and carbapenems were reacted with FOX-4 β-lactamase. UVD spectroscopy suggested the appearance of different chromophoric intermediates. Conclusions: Monocyclic β-lactam and carbapenem antibiotics are effective mechanism-based inhibitors of FOX-4 β-lactamase, a clinically important pmAmpC, and provide stimulus for the development of new inhibitors to inactivate plasmidic and chromosomal class C β-lactamases.
Papp-Wallace, Krisztina M.; Mallo, Susana; Bethel, Christopher R.; Taracila, Magdalena A.; Hujer, Andrea M.; Fernandez, Ana; Gatta, Julian A.; Smith, Kerri M.; Xu, Yan; Page, Malcolm G.P.; Desarbre, Eric; Bou, German; and Bonomo, Robert A., "A Kinetic Analysis of The Inhibition of FOX-4 β-Lactamase, A Plasmid-Mediated AmpC Cephalosporinase, By Monocyclic β-lactams and Carbapenems" (2014). Chemistry Faculty Publications. 165.
This is a pre-copyedited, author-produced version of an article accepted for publication in Journal of Antimicrobial Chemotherapy following peer review. The version of record Papp-Wallace, K. M.; Mallo, S.; Bethel, C. R.; Taracila, M. A.; Hujer, A. M.; Fernández, A.; Gatta, J. A.; Smith, K. M.; Xu, Y.; Page, M. G. P.; Desarbre, E.; Bou, G.; Bonomo, R. A. A kinetic analysis of the inhibition of FOX-4 β-lactamase, a plasmid-mediated AmpC cephalosporinase, by monocyclic β-lactams and carbapenems. Journal of Antimicrobial Chemotherapy 2013, 69, 682-690. is available online at: https://academic.oup.com/jac/article-lookup/doi/10.1093/jac/dkt434