Changing Epidemiology of Carbapenemases Among Carbapenem-Resistant Enterobacterales in a Greek Tertiary Care Hospital in Athens, 2020 to 2023

<b>Background:</b> Carbapenemase-producing Enterobacterales (CPEs) represent a significant global health threat, particularly in the context of nosocomial infections. The current study constitutes a retrospective epidemiological survey that aimed to provide updated data on the prevalence and characteristics of carbapenemases among carbapenem-resistant Enterobacterales (CREs) in a Greek tertiary hospital in Athens during and after the COVID-19 pandemic. <b>Results</b>: A total of 2021 non-duplicate CPE clinical isolates were detected. A significant increase in the number of carbapenemase-positive Enterobacterales was revealed during the study period (<i>p</i> < 0.05). KPC remained the predominant carbapenemase type through all four years of the survey, representing 40.7%, 39.9%, 53.5%, and 45.7% of the CPE isolates, respectively. However, a rapid transition from VIM to NDM metal-β-lactamase types was revealed, changing the epidemiological image of carbapenemases in the hospital setting. Notably, among the CPEs, antimicrobial resistance rates were significantly raised in the post-COVID-19 period (2022 and 2023) compared to the first study year (2020) for almost all the tested antibiotics, including those characterized as last-resort antibiotics. <b>Methods</b>: CREs were identified and subjected to screening for the five most prevalent carbapenemase genes [<i>Klebsiella pneumoniae</i> carbapenemase (KPC), Verona integron-borne metallo-β-lactamase (VIM), New Delhi metallo-β-lactamase (NDM), imipenemase (IMP), and oxacillin-hydrolyzing (OXA-48)] using a lateral flow immunoassay, and the CREs recovered from blood cultures were analyzed using a FilmArray system. Their clinical and epidemiological characteristics, as well as their antimicrobial susceptibility profiles, were also subjected to analysis <b>Conclusions</b>: Given this alarming situation, which is exacerbated by the limited treatment options, the development of new, effective antimicrobial agents is needed. The continued monitoring of the changing epidemiology of carbapenemases is also imperative in order to undertake rational public health interventions.