In vitro interactions of sulbactam/durlobactam in combination with meropenem, ceftazidime/avibactam, piperacillin/tazobactam, cefiderocol and fosfomycin against carbapenem-resistant Acinetobacter baumannii (CRAB) clinical isolates

We evaluated in vitro activity of sulbactam/durlobactam in combination with different antimicrobials against Carbapenem-Resistant Acinetobacter baumannii (CRAB) clinical isolates with different susceptibility profiles, including sulbactam/durlobactam-resistant strains. The genomes of 13 CRAB clinical isolates were characterized by whole-genome sequencing and synergy testing was performed with MIC Test Strips. Sulbactam/durlobactam, when combined with piperacillin/tazobactam or ceftazidime/avibactam, showed synergistic activity against 53.8% (7/13) of CRAB isolates and restored meropenem MIC values below the clinical breakpoint in 46.2% (6/13) of them. Our results demonstrate that sulbactam-durlobactam in combination with β-lactams exhibited high in vitro synergistic activity against CRAB strains.