Increasing proportions of extended-spectrum β-lactamase-producing isolates among Escherichia coli from urine and bloodstream infections: results from a nationwide surveillance network, Finland, 2008 to 2019

Abstract

Background<i>Escherichia coli</i> is the leading cause of urinary tract infections (UTI) and bloodstream infections (BSI), and the emergence of antimicrobial resistance (AMR) in <i>E. coli</i> causes concern.AimTo investigate changes in the proportion of extended-spectrum β-lactamase (ESBL) producing isolates among <i>E. coli</i> isolated from urine and blood in Finland during 2008-2019.MethodsSusceptibility testing of 1,568,488 urine (90% female, 10% male) and 47,927 blood <i>E. coli</i> isolates (61% female, 39% male) from all Finnish clinical microbiology laboratories during 2008-2019 was performed according to guidelines from the Clinical and Laboratory Standard Institute during 2008-2010 and the European Committee on Antimicrobial Susceptibility Testing during 2011-2019. A binomial regression model with log link compared observed trends over time and by age group and sex.ResultsThe annual proportion of ESBL-producing <i>E. coli</i> isolates among <i>E. coli</i> from blood cultures increased from 2.4% (23/966) to 8.6% (190/2,197) among males (average annual increase 7.7%; 95% CI: 4.4-11.0%, p < 0.01) and from 1.6% (28/1,806) to 6.4% (207/3,218) among females (9.3%; 95% CI: 4.8-14.0%, p < 0.01). In urine cultures, the proportion of ESBL-producing <i>E. coli</i> isolates increased from 2.2% (239/10,806) to 7.2% (1,098/15,297) among males (8.8%; 95% CI: 6.5-11.3%, p < 0.01) and from 1.0% (1,045/108,390) to 3.1% (3,717/120,671) among females (8.6%; 95% CI: 6.3-11.0%, p < 0.01). A significant increase was observed within most age groups.ConclusionsConsidering the ageing population and their risk of <i>E. coli</i> BSI and UTI, the increase in the annual proportions of ESBL-producing <i>E. coli</i> is concerning, and these increasing trends should be carefully monitored.