Relebactam Restores Aztreonam Activity Against Dual MBL/SBL-Producing Pathogens: An In Vitro Assessment
Hayashi K, et al. Journal of Global Antimicrobial Resistance, 2025, 42, 73-79.
In this study, the in vitro efficacy of relebactam in combination with aztreonam was evaluated against 119 carbapenemase-producing Gram-negative clinical isolates, including those co-producing IMP-type metallo-β-lactamases (MBLs) and serine-β-lactamases (SBLs), frequently encountered in Japan. Minimum inhibitory concentrations (MICs) were determined using the broth microdilution method for aztreonam, imipenem, and their combinations with relebactam or avibactam. The aztreonam/relebactam combination markedly reduced MICs across strains harboring both MBLs and SBLs, including E. coli, K. pneumoniae, and Enterobacter spp. Notably, this combination also exhibited strong activity against Stenotrophomonas spp. The MICs of aztreonam/relebactam were significantly lower than aztreonam alone and comparable to aztreonam/avibactam. These findings highlight the experimental potential of relebactam to restore aztreonam activity against multidrug-resistant strains, offering a viable treatment option in regions lacking ceftazidime-avibactam access.
