Aztreonam-avibactam (ATM-AVI) and ceftazidime-avibactam plus aztreonam (CAZ/AVI-ATM) represent therapeutic strategies for infections caused by metallo-lactamase (MBL)-producing Enterobacterales.This perspective synthesizes mechanistic rationale, microbiologic determinants of activity, pharmacokinetic/pharmacodynamic principles, and available clinical outcomes to compare these regimens and identify knowledge gaps.Both approaches are expected to provide activity against MBL-producing organisms; however, important distinctions exist.ATM-AVI ensures fixed and predictable co-exposure of aztreonam and avibactam, minimizing the risk of pharmacokinetic asynchrony inherent to administering CAZ/AVI with separate aztreonam.The efficacy of ATM-AVI may nevertheless be influenced by organism-specific resistance mechanisms and pharmacologic variables.CAZ/AVI-ATM offers a pragmatic alternative but introduces logistical complexity and potential variability in inhibitor exposure.Observational data appear more favorable for ATM-AVI, although direct comparisons are not available.In the absence of direct comparative trials, regimen selection should consider renal function, infection syndrome, and the feasibility of sustaining adequate inhibitor exposure.
Giuliano et al. (2026) studied this question.