Clinical Epidemiology and Antimicrobial Susceptibility of Carbapenemase-Producing Enterobacterales from a German University Hospital During a 5-Year Period

The primary purpose of this study was to assess the prevalence and the antimicrobial susceptibility rates of carbapenemase-producing Enterobacterales (CPE) in a German University Hospital during a 5-year period. From January 2020 to December 2024, all Enterobacterales detected were molecularly investigated for carbapenemases in every case of elevated minimum inhibitory concentration of ertapenem, meropenem, or imipenem. Subsequently, CPE were tested for susceptibility to reserve antibiotics. Overall, 101 CPE were identified. Most of the CPE strains harbored only one carbapenemase gene, such as <i>bla_OXA-48</i> (<i>n</i> = 32, 31.6%), <i>bla_NDM</i> (<i>n</i> = 27, 26.7%), and <i>bla_VIM</i> (<i>n</i> = 14, 13.8%). The annual number of CPE detected increased during the observation period (2020, <i>n</i> = 5; 2021, <i>n</i> = 5; 2022, <i>n</i> = 24; 2023, <i>n</i> = 29; 2024, <i>n</i> = 38). We also observed a progressive rise of the proportion of CPE harboring a metallo-β-lactamase gene such as <i>bla_NDM</i> or <i>bla_VIM</i> (2020, 0.0%; 2021, 0.0%; 2022, 50.0%; 2023, 55.2%; 2024, 65.8%). Regarding the antimicrobial susceptibility, only 3.3% of all CPE isolates tested showed resistance to aztreonam/avibactam. In contrast, the resistance rates for cefiderocol and ceftazidime/avibactam amounted respectively to 12.8% and 53.9%. The increasing annual number of CPE at our hospital is associated with a rise of the proportion of metallo-β-lactamase-producing strains. The newly available antibiotic aztreonam/avibactam showed promising <i>in vitro</i> activity against CPE.