Epidemiology of bloodstream infections caused by extended-spectrum cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae in Switzerland, 2015-2022: secular trends and association with the COVID-19 pandemic

Abstract

Purpose: The association between the COVID-19 pandemic and the incidence of invasive infections caused by multidrug-resistant organisms remains a topic of debate. The aim of this study was to analyse the national incidence rates of bloodstream infections (BSI) caused by Escherichia coli (EC) and Klebsiella pneumoniae (KP) with extended-spectrum cephalosporin-resistance (ESCR) in two distinct regions in Switzerland, each exhibiting varying antimicrobial resistance patterns and that were impacted differently by the pandemic. Methods: We analysed data of positive blood cultures prospectively collected by the nationwide surveillance system (ANRESIS) from January 1, 2015, to August 31, 2022. To explore the potential relationship between COVID-19 patient occupancy and ESCR incidence rates, we conducted an in-depth analysis over the two-year pandemic period from April 1, 2020, to March 30, 2022. We employed Quasi-Poisson and logistic regression analyses to investigate these associations. Results: During the study period, a total of 40997 EC-BSI and 8537 KP-BSI episodes were collected and reported to ANRESIS by the participating hospitals. ESCR was observed in 11% (n=4313) of E. coli and 8% (n=664) of K. pneumoniae, respectively. A significant reduction in ESCR-EC BSI incidence occurred during the pandemic in the region with the highest COVID-19 incidence. Conversely, ESCR-KP BSI incidence initially fell considerably and then increased during the pandemic in both regions; however, this effect was not statistically significant. Conclusion: In the early phase of the COVID-19 pandemic, a decrease in ESCR rates was observed, particularly in ESCR-EC BSI within the most heavily impacted region.