Incidence of community-onset extended-spectrum β-lactamase-producing <i>Escherichia coli</i> and <i>Klebsiella pneumoniae</i> infections: an 11-year population-based study in Denmark

<b>Background:</b> Data elucidating trends of community-onset extended-spectrum β-lactamase (ESBL)-producing <i>Escherichia coli</i> and <i>Klebsiella pneumoniae</i> infections remain sparse in low prevalence areas. We conducted a population-based study to determine the incidence, temporal trends and co-resistance of community-onset ESBL infections. <b>Methods:</b> We identified all recorded episodes of <i>E. coli</i> and <i>K. pneumoniae</i> bacteraemia and urinary tract infections in adult patients (&gt;15 years) in the North Denmark Region between 2007–2017. Using population-based registries, we obtained information on demographics and place of acquisition, and investigated the standardized incidence rates and temporal trends of community-onset ESBL infections and the associated patterns of co-resistance. <b>Results:</b> A total of 3741 episodes of community-onset ESBL <i>E. coli</i> or <i>K. pneumoniae</i> infections were observed during the study period, with the annual standardized incidence rate increasing from 7.5 to 105 per 100,000 person-years between 2007–2017. The increase was conveyed primarily by a rise in <i>E. coli</i> urinary tract infections shifting from being mainly healthcare-associated to community-acquired. ESBL-producing isolates increased from 0.5 to 4.0% with considerable co-resistance. <b>Conclusion:</b> The proportion of <i>E. coli</i> and <i>K. pneumoniae</i> isolates producing ESBL have increased considerably in the North Denmark Region. The increasing incidence and frequent co-resistance should raise awareness among physicians responsible for empirical antibiotic treatment.