Cefepime and New Cefepime/Beta-Lactamase Inhibitor Combination for the Treatment of Gram-Negative Bacteria: Chemical Structure and Mechanism of Action, Microbiological Target, Clinical Use and PK/PD Characteristics

The global spread of multidrug-resistant (MDR) Gram-negative bacteria, particularly extended-spectrum β-lactamase (ESBL)- and carbapenemase-producing Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii, presents a significant public health challenge by limiting effective antimicrobial treatment options. Cefepime, a fourth-generation cephalosporin with broad-spectrum activity, is increasingly compromised by β-lactamase production, efflux pumps, and porin loss. In response, novel cefepime-based β-lactam/β-lactamase inhibitor (BL/BLI) combinations have been developed to overcome these resistance mechanisms. This review examines preclinical and clinical studies on cefepime-based BL/BLI combinations, specifically cefepime/enmetazobactam, cefepime/taniborbactam, cefepime/zidebactam, and cefepime/nacubactam, as found in the PubMed database. Key findings include the restoration of activity against class A ESBLs with cefepime/enmetazobactam, while cefepime/taniborbactam and cefepime/zidebactam show broader inhibition of serine β-lactamases and selected metallo-β-lactamases. Additionally, zidebactam and nacubactam target penicillin-binding protein 2, enhancing bactericidal potency. Preclinical and early-phase clinical trial data indicate potent in vitro activity and favorable pharmacokinetic/pharmacodynamic (PK/PD) profiles. Specifically, the combination of cefepime with enmetazobactam has demonstrated an optimal Cmax/MIC ratio of 8–10, supporting its efficacy in treating MDR Gram-negative infections. Phase III studies are ongoing to confirm efficacy in complicated infections. Cefepime-based BL/BLI combinations are emerging as promising carbapenem-sparing agents, offering broad-spectrum activity, dual mechanisms of action, and encouraging clinical outcomes. These findings support their inclusion in antimicrobial stewardship strategies aimed at mitigating resistance.