Epidemiology and risk factors of Escherichia coli bloodstream infections associated with extended-spectrum beta-lactamase production: a national surveillance and data linkage study, Finland, 2018 to 2023.

BACKGROUNDEscherichia coli (EC) is the leading cause of bloodstream infections (BSI). The emergence of extended-spectrum beta-lactamase (ESBL) production in EC is concerning, as it may worsen infection outcomes.AIMWe aimed to assess the incidence and outcome of ESBL-EC and non-ESBL-EC BSIs in Finland in 2018-2023 and identify factors associated with death.METHODSData from national registers were used to identify EC BSIs and to determine infection origin, patient comorbidities and death within 30 days. Isolates resistant or susceptible with increased exposure to third-generation cephalosporins were defined as ESBL-producing. Trends were analysed using a binomial regression model with log link. Factors associated with 30-day case-fatality were evaluated using a multivariable logistic regression model.RESULTSIn total, 33,586 EC BSIs were identified, of which 1,916 (5.7%) were ESBL-EC BSIs. The annual incidence of ESBL-EC BSIs decreased from 7.2/100,000 to 4.9/100,000, being 3.3-fold larger for healthcare-associated than community-acquired ESBL-EC BSIs. Non-ESBL-EC BSIs showed similar but weaker trends. The 30-day case-fatality rate was 1.3-fold higher for ESBL-EC than non-ESBL-EC BSIs and 1.7-3.2-fold higher for healthcare-associated than community-acquired BSIs. Factors associated with 30-day case-fatality included age, comorbidity, male sex, and healthcare association and ESBL in patients with no or less severe comorbidities.CONCLUSIONWe observed a decline in EC BSIs in Finland in 2018-2023, especially those caused by ESBL-EC and healthcare-associated BSIs. ESBL-EC BSIs were associated with 30-day case-fatality only among patients with low comorbidity, a phenomenon requiring further investigation. Continuous surveillance of BSI pathogens, also covering BSI outcome, is essential.