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Table 2 Features of Eight Outbreaks of Verotoxigenic Escherichia coli O157:H7 Characterized by Whole Genome Sequencing in Canada

From: Evaluation of whole-genome sequencing for outbreak detection of Verotoxigenic Escherichia coli O157:H7 from the Canadian perspective

  Number of Genetic Differences Among Outbreak-Related Isolates
Outbreak Year Number of Lab Confirmed Cases Suspect / Confirmed Source Number of Implicated
PFGE Patterns / MLVA Profilesd
Number of Isolates Sequenced in the Study SNVs wgMLST alleles
1 2011 14 Raw shelled walnuts 1 / 2 14 0–3 0–4
2 2011 2 In-shell hazelnuts 1 / 2 2 0 4
3a 2012 15 Preformed beef patties 6 / 8 42b Group 1c: 0–1
Group 2c: 0–1
Group 3d: 0
Group 4: 0–3
Group 5c: 0–1
Group 6d: 0
All Isolates: 0–110
Group 1c: 1–5
Group 2c: 0–3
Group 3d: 1–4
Group 4: 0–9
Group 5c: 1–3
Group 6d: 2–4
All Isolates: 0- > 100
4 2012 23 Romaine
lettuce
2 / 1 23 0–1 0–7
5 2012 18 Beef products 1 / 1 25b 0–3 0–4
6a 2012 9 Frozen beef burgers 7 / 8 36b Group 1d: 0–2
Group 2d: 0
Group 3d: 0–1
All Isolates: 0–106
Group 1d: 0–4
Group 2d: 0–3
Group 3d: 0–2
All Isolates: 0- > 90
7 2012 31 Fast Food
lettuce
3 / 1 31 0–2 0–8
8 2013 28 Raw milk cheese 4 / 4 44b 0–5 0–9
  1. PFGE pulsed-field gel electrophoresis, MLVA multilocus variable-number tandem-repeat analysis, SNVs single nucleotide variants, wgMLST whole-genome multilocus sequence typing
  2. aSuspected multi-strain event; isolates split into multiple groupings and one or more potential outliers
  3. bOne or more food isolates were sequenced
  4. cOnly includes food isolates
  5. dContains clinical and food isolates