Incidence of colonization and infection with carbapenemase-producing Enterobacterales in Toronto and Peel Region, Ontario, 2007–2024

Background: Carbapenemase-producing Enterobacterales (CPE) are an urgent public health threat. Monitoring changes in the epidemiology of CPE is critical to the development of action plans against antimicrobial resistance. Methods: The Toronto Invasive Bacterial Diseases Network (TIBDN) has conducted population-based surveillance for CPE in Toronto and Peel Region, Ontario, since its first identification in the population in 2007. Laboratories report all isolates of CPE to the study; confirmation of CPE is by polymerase chain reaction (PCR). Population data are obtained from Statistics Canada. This analysis includes data from 2007 to 2024. Results: The incidence of CPE colonization/infection increased steadily from 0.03/100,000/year to 3.99/100,000/year in 2024, with the exception of the pandemic years (2020–2021). The incidence was higher in Peel Region than Toronto (average IRR 2.2, range 1.8–2.5), with the exception of 2020, when the decrease in Peel Region (IRR 0.51, 95% CI 0.30–0.83) was greater than Toronto (IRR 0.86, 95% CI 0.54–1.38). Escherichia coli- and Klebsiella pneumoniae-producing bla NDM and/or bla OXA-48-like were dominant. The proportion of cases first identified in hospital laboratories as colonized increased from 45.6% (67/147) in 2010–2014 to 75.1% (948/1263) in 2020–2024. Of 273 patients rectally colonized with CP- K. pneumoniae, 50 (18%) had a clinical isolate, and 20 (7%) became bacteremic a median of 35 and 53 days later, respectively. Conclusion: The incidence of CPE increased steadily after first detection, although cases decreased during the pandemic. Post-pandemic, substantial increases occurred in both population areas. Screening for colonization can identify patients at increased risk of infection. Improved transmission control programs are needed to mitigate the impact of CPE.