Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.
Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.
Int J Antimicrob Agents. 2021 Jan;57(1):106228. doi: 10.1016/j.ijantimicag.2020.106228. Epub 2020 Nov 24.
This study aimed to investigate the in vitro activity of taniborbactam (VNRX-5133), a novel broad-spectrum bicyclic boronate, against NDM-1 and Q119E, Q119K, Q119C, Q119F, Q119V, and Q119Y NDM-1 variants, which showed an increased activity towards some β-lactams, including cefepime.
Inhibition kinetic assays were spectrophotometrically performed using cefepime (50 μM) as the reporter substrate and 80 nM of each enzyme. Taniborbactam behaves as a competitive inhibitor towards NDM-1 and NDM-1 Q119 variants with lower Ki values (range 3-16 nM). The phenotypic profile was assessed in both Enterobacterales clinical isolates and engineered Escherichia coli BL21(DE3) strains by conventional broth microdilution procedures according to the Clinical and Laboratory Standards Institute (CLSI).
Taniborbactam at a fixed concentration of 4 mg/L was able to restore activity of cefepime in 24 of 26 Enterobacterales clinical isolates harbouring metallo-β-lactamases with MIC/MIC values of 14 mg/L. Cefepime MICs were drastically reduced in all clinical isolates and in NDM-1 and Q119X producing Escherichia coli BL21(DE3). Taniborbactam was unable to restore susceptibility to cefepime in two IMP variants producing clinical isolates.
The inhibition level of NDM enzymes provided by taniborbactam protects the antibacterial activity of cefepime from this important metallo-β-lactamase.
本研究旨在研究新型广谱双环硼酸化合物替那博林（VNRX-5133）对 NDM-1 及其 Q119E、Q119K、Q119C、Q119F、Q119V 和 Q119Y 等 NDM-1 变异体的体外活性，这些变异体对一些β-内酰胺类药物（包括头孢吡肟）的活性有所增加。
采用分光光度法抑制动力学试验，以头孢吡肟（50 μM）为报告底物，使用 80 nM 浓度的每种酶进行检测。替那博林对 NDM-1 和 NDM-1 Q119 变异体表现为竞争性抑制剂，其 Ki 值较低（范围为 3-16 nM）。根据临床和实验室标准协会（CLSI）的常规肉汤微量稀释程序，在肠杆菌科临床分离株和工程化大肠杆菌 BL21(DE3)菌株中评估表型特征。
替那博林在固定浓度 4 mg/L 时，能够恢复 26 株携带金属β-内酰胺酶的肠杆菌科临床分离株中 24 株对头孢吡肟的活性，MIC/MIC 值为 14 mg/L。所有临床分离株和产生 NDM-1 和 Q119X 的大肠杆菌 BL21(DE3)中，头孢吡肟 MIC 值均大幅降低。替那博林无法恢复两种产生临床分离株的 IMP 变异体对头孢吡肟的敏感性。
替那博林对 NDM 酶的抑制水平保护了头孢吡肟的抗菌活性免受这种重要的金属β-内酰胺酶的影响。
