Diversity in Carbapenemases in Enterobacterales in Southeastern Austria Before and During the COVID-19 Pandemic

The COVID-19 pandemic has profoundly influenced healthcare systems and infection control worldwide, with important implications for the epidemiology of antimicrobial resistance. This study examined the prevalence and characteristics of carbapenem-resistant Enterobacterales (CRE) isolates in Southeastern Austria from 2018 to 2022 to assess potential pandemic-related effects. A total of 63 isolates were analyzed using phenotypic and molecular methods, including carbapenemase detection, genotyping, and multilocus sequence typing. The number of CRE isolates appeared to decline during the pandemic years (2021-2022) compared to the pre-pandemic period, with <i>Enterobacter cloacae</i> notably detected in both full pandemic years. Carbapenemase-producing CRE accounted for 44 out of the 63 isolates (69.8%), with metallo-beta-lactamases (VIM-1 and NDM-1) and OXA-48-like carbapenemases predominating. Resistance mechanisms not based on carbapenemase production were more common before the pandemic but rarely detected thereafter. To our knowledge, this is the first report of dual-carbapenemase-producing CRE isolates in Austria. Multi-locus-sequence typing indicated limited nosocomial transmission, with most isolates representing independent introductions linked to external sources. The decline in CRE prevalence may reflect reduced international travel and healthcare access during the pandemic, which could have limited the importation of resistant strains. These findings reflect the potential role of global mobility in the spread of CRE and illustrate how public health interventions can shape antimicrobial resistance trends.