Cefepime-Zidebactam, a Novel Option for AMR Infections

This episode, "Cefepime-Zidebactam, a Novel Option for AMR Infections," features a look at the newest addition to the gram-negative pipeline. Cefepime-zidebactam stands apart from the growing list of beta-lactam-beta-lactamase inhibitor combinations because its partner compound does more than protect the beta-lactam. Dr. Tamma introduces the agent, recently approved and expected to reach clinical use in early 2027, and asks Dr. Shields to explain how it works and why its mechanism matters for clinical decision-making.

Dr. Shields acknowledges that the expanding roster of combination agents can be difficult to keep straight, and suggests that cefepime-zidebactam's distinctive mechanism will help clinicians differentiate it. He explains that zidebactam belongs to the diazabicyclooctane family but carries a unique chemical structure that allows it to function as a beta-lactam enhancer, exerting its own antibacterial effect by binding penicillin-binding protein 2. Because cefepime primarily targets penicillin-binding protein 3, Dr. Shields describes the combination as delivering complementary binding at two sites, a feature he expects will shape how clinicians think about using it. He notes that zidebactam inhibits class A and class C enzymes but not KPC or metallo-beta-lactamases, yet the combination still demonstrates in vitro activity against those organisms through the enhancer effect. He highlights a particularly strong signal in animal models that standard susceptibility testing may not fully capture.

Dr. Tamma summarizes the evidence base, describing consistent killing in animal models across Pseudomonas, Acinetobacter, and carbapenemase-producing Enterobacterales, alongside encouraging but uncontrolled observational experience in carbapenem-resistant infections. She adds that zidebactam lacks a beta-lactam ring, so metallo-beta-lactamases cannot hydrolyze it even though it does not inhibit them. Clinicians should follow cefepime-zidebactam closely as comparative clinical data accumulate after its launch.

Dr. Pogue revisits the established options for serine carbapenemase producers in "Treating KPC and OXA-48-Like Carbapenemase Producers."