Abstract
Global expansion of antimicrobial drug–resistant Escherichia coli sequence type (ST) 131 is unrivaled among human bacteria. Understanding trends among ST131 clades will help with designing prevention strategies. We screened E. coli from blood samples (n = 1,784) obtained in Calgary, Alberta, Canada, during 2006, 2012, and 2016 by PCR for ST131 and positive samples (n = 344) underwent whole-genome sequencing. The incidence rate per 100,000 residents increased from 4.91 during 2006 to 12.35 during 2012 and 10.12 during 2016. ST131 belonged to clades A (10%), B (9%), and C (81%). Clades C1-nonM27 and B were common during 2006, and C2 containing blaCTX-M-15, C1-M27 containing blaCTX-M-27, and A were responsible for the increase of ST131 during 2012 and 2016. C2 was the most antimicrobial drug–resistant subclade and increased exponentially over time. Eradicating ST131, more specifically the C2 subclade, will lead to considerable public health benefits for persons in Calgary.
Highlights
Global expansion of antimicrobial drug–resistant Escherichia coli sequence type (ST) 131 is unrivaled among human bacteria
The abrupt global expansion of ST131 during the 2000s is unrivaled among human bacteria and is a real-world model for the evolution of antimicrobial-resistant high-risk clones (10)
This study describes the clinical features, incidence rates, genomic characteristics, and changes in population structure of ST131 clades causing bloodstream infections in a large centralized region of Canada over an 11-year period (2006–2016)
Summary
Global expansion of antimicrobial drug–resistant Escherichia coli sequence type (ST) 131 is unrivaled among human bacteria. ST131 is the most dominant and most antimicrobial-resistant among E. coli causing bloodstream infections in Calgary, Alberta, Canada, infecting mostly the elderly in long-term care centers (7). Limited information is available regarding the changes in population dynamics of ST131 clades over extended periods, especially among nonbiased E. coli isolates in large, well-defined, geographic regions. To address this issue, we conducted a retrospective cohort study that characterized ST131 clades responsible for bloodstream infections in Calgary over an 11-year period (2006–2016). Investigating trends of ST131 clades over long periods by using a populationbased surveillance approach will aid in clarifying the evolution of this clone and help with designing superior prevention strategies (3,10)
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