Bacteriological analysis of wheat flour associated with an outbreak of Shiga toxin-producing Escherichia coli O121.

A 2016/2017 outbreak of Shiga toxin-producing Escherichia coli (STEC) O121 in Canada, was linked to wheat flour, milled at a single facility on three consecutive days in October 2016. Most Probable Number (MPN) estimates of the concentration of STEC O121 in the recalled flour were made using the results of qualitative testing conducted during the outbreak investigation and from analysis of 5 × 2.5 g, 5 × 25 g and 5 × 100 g analytical units of the recalled flour.