In vitro activity of AVE1330A, an innovative broad-spectrum non-β-lactam β-lactamase inhibitor

Abstract

Objectives: Production of β-lactamases is the main mechanism of β-lactam resistance in Gram-negative bacteria. Despite the current use of clavulanic acid, sulbactam and tazobactam, the prevalence of class A and class C enzymes is increasing worldwide, demanding new β-lactamase inhibitors. Here we report the antimicrobial properties of AVE1330A, a representative of a novel class of bridged bicyclico[3.2.1]diazabicyclo-octanones in combination with ceftazidime. Materials and methods: IC50 and kinetic parameters of the hydrolysis reaction were used to characterize β-lactamase inhibition by AVE1330A. MICs for >600 strains were determined with the combination ceftazidime/AVE1330A at a fixed ratio of 4:1. Results: IC50s of AVE1 330A for TEM-1 and P99 enzymes were 0.0023 mg/L (8 nM) and 0.023 mg/L (80 nM), compared with 0.027mg/L (130 nM) and 205.1mg/L (1 × 106 nM) of clavulanic acid and 0.013mg/L (40 nM) and 1.6mg/L (5000 nM) of tazobactam. A highly stable covalent complex led to a low turnover of AVE1330A. MICs of ceftazidime/AVE1330A for Enterobacteriaceae were at least eight-fold lower than those of ceftazidime alone. All of the Escherichia coli, Klebsiella pneumoniae, Citrobacter and Proteus mirabilis strains, including ceftazidime-resistant isolates, were inhibited at 4-8 mg/L. Only 2 mg/L were required to inhibit other Proteeae, Enterobacter, Salmonella and Serratia. Conclusion: The combination of cettazidime with AVE1330A exhibited broad-spectrum activity against Ambler class A- and class C-producing Enterobacteriaceae. © The Bristish Society for Antimicrobial Chemotherapy 2004; all rights reserved.