Microbiological Survey of Wheat Flour Sold at Retail in Canada, 2018-2019

​Following two O121 Shiga Toxin-Producing Escherichia coli (STEC) outbreaks linked to wheat flour, this study was conducted to gain baseline information on the occurrence of bacterial pathogens and levels of indicator organisms in wheat flour in Canada. A total of 347 pre-packaged wheat flour samples were analyzed for Salmonella species (spp.), STEC, Listeria monocytogenes (L. monocytogenes), aerobic colony count (ACC), total coliforms and generic Escherichia coli (E. coli). Salmonella spp. and O157 STEC were not detected in any of the samples. L. monocytogenes was identified in two samples (0.6%) and non-O157 STEC was isolated from 6 (1.7%) samples. ACC, total coliforms and generic E.coli were detected (≥0.48 log CFU/g) in 98.8%, 72.6% and 0.6% of the flour samples respectively.