Susceptibility Assessment and Review of Novel Beta-Lactam/Beta-Lactamase Inhibitor against Carbapenem-Resistant Enterobacterales

Background/Aims: Carbapenem-resistant Enterobacterales (CRE) infections represent a significant global health concern, characterized by low susceptibility rate- and adverse effect-related high mortality and limited treatment options. Novel beta-lactam/beta-lactamase inhibitors (BLBLIs) are first-line therapeutic agents against specific carbapenemase (CP)-producing CREs. We assessed current CRE susceptibility to these novel BLBLIs to aid optimal antimicrobial stewardship, emphasizing the need for continuous resistance surveillance.Methods: In total, we identified 71 CRE isolates based on the imipenem minimum inhibitory concentration and disk diffusion susceptibility testing for imipenem, meropenem, and ertapenem. We performed antimicrobial susceptibility testing for novel BLBLIs, including ceftazidime-avibactam, imipenem-relebactam, and meropenem-vaborbactam as well as CP gene molecular characterization for all CRE isolates.Results: We analysed a total of 71 CRE isolates and our CP genotypic analysis identified 46 Klebsiella pneumoniae CP (KPC)-producing, 10 New Delhi metallo-beta-lactamase-producing, and two oxacillinase-48-like producing isolates. We identified the remaining 13 isolates as non-CP-producing CREs. The susceptibility rates for ceftazidime-avibactam, imipenem-relebactam, and meropenem-vaborbactam were 84.5%, 80.3%, and 83.1%, respectively. Among the CP-producing isolates, KPC producers exhibited susceptibility rates of 97.8%, 93.5%, and 95.7% to ceftazidime-avibactam, imipenem-relebactam, and meropenem-vaborbactam, respectively.Conclusions: Novel BLBLIs generally yielded high CRE susceptibility rates, with the latter exceeding 90% in KPC-producing isolates. Although these findings indicate the efficacy of novel BLBLIs in treating CRE infections, ongoing surveillance is essential to detect and mitigate resistant strain emergence.