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. 2025 Aug 28;80(Supplement_2):ii45-ii53.
doi: 10.1093/jac/dkaf220.

Increasing rates of ESBL-producing Escherichia coli and Klebsiella pneumoniae in Canadian Hospitals: 17 years of the CANWARD study, 2007-23

Philippe Lagacé-Wiens  1   2 , Laura Mataseje  3 , Melissa McCracken  3 , Andrew Walkty  1   2   4 , James A Karlowsky  1   2 , Heather J Adam  1   2 , Melanie Baxter  1 , Andrew Denisuik  5 , George G Zhanel  1
Affiliations

Increasing rates of ESBL-producing Escherichia coli and Klebsiella pneumoniae in Canadian Hospitals: 17 years of the CANWARD study, 2007-23

Philippe Lagacé-Wiens et al. J Antimicrob Chemother. .

Abstract

Objectives: ESBL-producing Escherichia coli and Klebsiella pneumoniae are major causes of infections, including urinary tract, abdominal, nosocomial pneumonia, diabetic foot and bloodstream infections. This study examines trends in their prevalence, genotypes and antibiotic susceptibility and identifies at-risk populations.

Methods: Between 2007 and 2023, bacterial isolates were collected from sentinel laboratories (CANWARD study). Identification, antimicrobial susceptibility testing and WGS were performed. Trends in incidence, resistance patterns, beta-lactamase genotypes and demographic associations were analysed using multifactorial regression and trend analysis.

Results: Among 11 931 E. coli and 3973 K. pneumoniae isolates, 8.4% and 5.6%, respectively, were ESBL-producers, with prevalence increasing from 2007-08 to 2021-23 (E. coli: 3.6% to 11.8%; K. pneumoniae: 2.2% to 8.0%; P < 0.001). Susceptibility among ESBL E. coli declined for amoxicillin-clavulanate (78.7% to 28.6%) but increased for gentamicin (43.5% to 70.3%) (P < 0.001). MDR among ESBL-positive E. coli declined (82.4% to 63.4%; P < 0.001) but remained stable among ESBL-positive K. pneumoniae. ESBL E. coli was associated with inpatients, respiratory specimens and males, while K. pneumoniae was linked to inpatient status and regional variations. Genotypic analysis showed increasing blaCTX-M-15 in K. pneumoniae and blaCTX-M-27 in E. coli. blaOXA-1 and blaTEM-1 were associated with MDR and first-generation β-lactam/β-lactamase inhibitor resistance.

Conclusion: ESBL E. coli and K. pneumoniae have increased in prevalence, with evolving resistance patterns. While MDR in E. coli has declined, resistance to key antimicrobials, including sulphonamides, fluoroquinolones and first-generation β-lactam/β-lactamase inhibitors remains high. Resistance rates varied significantly by region of Canada and by inpatient status, sex and specimen type.

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