An Outbreak of Shiga Toxin–Producing Escherichia coli O121 Infections Associated with Flour — Canada, 2016–2017

On Dec 29, 2016, PulseNet Canada identified a cluster of six Escherichia coli non-O157 isolates with a matching pulsed-field gel electrophoresis (PFGE) pattern combination that was new to the PulseNet Canada database. The patients resided in three geographically distinct provinces. In January 2017, the Public Health Agency of Canada initiated an investigation with local, provincial, and federal partners to investigate the source of the outbreak. In March 2017, E. coli O121 with the outbreak PFGE pattern was isolated from an open flour sample from a patient's home and a closed sample collected at a retail store, both of the same brand and production date. The clinical and flour isolates grouped together, with only 0-6 whole genome multilocus sequence typing allele differences.