Risk factors of community-onset extended-spectrum β-lactamase Escherichia coli and Klebsiella pneumoniae bacteraemia: an 11-year population-based case-control-control study in Denmark.

Objectives: To investigate and explore temporal changes in risk factors of community-onset extended-spectrum β-lactamase (ESBL) Escherichia coli and Klebsiella pneumoniae bacteraemia in a region with low antibiotic resistance.

Methods: Population-based case-control study including 223 cases hospitalized with a first-time community-onset ESBL-producing E. coli and K. pneumoniae bacteraemia, 2214 non-ESBL E. coli and K. pneumoniae bacteraemia controls, and 2228 population controls in the North Denmark Region between 2007 and 2017. We used a conditional logistic regression to compute crude and adjusted (age, gender and co-morbidity) odds ratios (aORs) and 95% CIs of risk factors and compared selected risk factors between 2007-2011 and 2016-2017.

Results: Several conventional risk factors of ESBL E. coli or K. pneumoniae were identified compared with the population controls. Compared with the non-ESBL controls, use of fluoroquinolones (aOR 3.56, 95% CI 2.52-5.05), three or more admissions within the recent year (aOR 2.18, 95% CI 1.45-3.28), three or more antibiotic prescriptions within 15-365 days before the admission (aOR 2.18, 95% CI 1.53-3.10), male sex (aOR 2.01, 95% CI 1.50-2.69), admission within 1-91 days (aOR 1.84, 95% CI 1.37-2.48) and antibiotic within 15-91 days (aOR 1.82, 95% CI 1.37-2.42) inferred the highest risk. Assessment of temporal dynamics between 2007-2011 and 2016-2017 revealed a slight reduction in risk factors associated with direct health-care contact (e.g. hospital admission).

Conclusions: Recent and frequent hospitalization, and exposure to antibiotics, especially use of fluoroquinolones, appeared to be associated specifically with ESBL production, and focus and interventions should be directed towards these areas. Our results indicated a dissemination of ESBLs into the community.