Interaction of Avibactam with Class B Metallo-β-Lactamases

Abstract

β-Lactamases are the most important mechanisms of resistance to the β-lactam antibacterials. There are two mechanistic classes of β-lactamases: the serine β-lactamases (SBLs) and the zinc-dependent metallo-β-lactamases (MBLs). Avibactam, the first clinically useful non-β-lactam β-lactamase inhibitor, is a broad-spectrum SBL inhibitor, which is used in combination with a cephalosporin antibiotic (ceftazidime). There are multiple reports on the interaction of avibactam with SBLs but few such studies with MBLs. We report biochemical and biophysical studies on the binding and reactivity of avibactam with representatives from all 3 MBL subfamilies (B1, B2, and B3). Avibactam has only limited or no activity versus MBL-mediated resistance in pathogens. Avibactam does not inhibit MBLs and binds only weakly to most of the MBLs tested; in some cases, avibactam undergoes slow hydrolysis of one of its urea N-CO bonds followed by loss of CO2, in a process different from that observed with the SBLs studied. The results suggest that while the evolution of MBLs that more efficiently catalyze avibactam hydrolysis should be anticipated, pursuing the development of dual-action SBL and MBL inhibitors based on the diazabicyclooctane core of avibactam may be productive.

Cyclic Boronates Inhibit All Classes of β-Lactamases

“…Inhibition of BcII by cyclic boronate 2 is comparable in potency to that by thiomandelic acid, while cyclic boronate 2 is around 10 times more potent than thiomandelic acid against VIM-1. Avibactam is a potent inhibitor of SBLs but, notably, is hydrolyzed slowly by some MBLs (19, 41). The time courses of cyclic boronate inhibition against the enzymes tested demonstrated no time dependence for inhibition of the MBLs, at least under our experimental conditions.…”

“…The MBLs are able to hydrolyze all classes of β-lactam except for monobactams (18). The ability of the MBLs to hydrolyze SBL inhibitors, including avibactam (19), is a growing problem in the treatment of infections where both SBL- and MBL-mediated cephalosporin and carbapenem resistance have been acquired (20). To date there are no clinically approved MBL inhibitors.…”

19F‐NMR Reveals the Role of Mobile Loops in Product and Inhibitor Binding by the São Paulo Metallo‐β‐Lactamase

“…A clear chemical‐shift change was observed with avibactam and Y58C* but not F151C*, thus indicating that avibactam binding induces changes in the L3 region but not the α3 region (Figures S25,26). With Y58C*, a shift back to the original protein peak was observed after 12 h, likely as a result of slow hydrolysis of avibactam catalyzed by SPM‐1 4b. Addition of fresh avibactam to the reacted solution shifted the peak towards that arising originally from avibactam with Y58C*.…”

“…We then tested the utility of PrOF NMR for monitoring the binding of weak SPM‐1 inhibitors, as exemplified by avibactam, which inhibits class A, C, and some D β‐lactamases,3, 4c but has low affinity for most MBLs 4b. A clear chemical‐shift change was observed with avibactam and Y58C* but not F151C*, thus indicating that avibactam binding induces changes in the L3 region but not the α3 region (Figures S25,26).…”

Two for the price of one: emerging carbapenemases in a returning traveller to New York City

“…We used synergy testing results and studies supporting aztreonam plus ceftazidime-avibactam combination therapy to guide our clinical management 16–20. The serine carbapenemase inhibitor, avibactam, is ineffective against MBLs; however, aztreonam has in vitro activity against the MBLs 21. The potent activity of this combination may be mediated by the preservation of aztreonam activity by avibactam.…”