Wheat flour has recently been recognised as an exposure vehicle for the foodborne pathogen Shiga toxin-producing Escherichia coli (STEC). Wheat flour milled on two sequential production days in October 2016, and implicated in a Canada wide outbreak of STEC O121:H19, was analysed for the presence of STEC in November 2018. Stored in sealed containers at ambient temperature, the water activity of individual flour samples was below 0.5 at 6 months post-milling and remained static or decreased slightly in individual samples during 18 months of additional storage. STEC O121 was isolated, with the same genotype (stx2a, eae, hlyA) and core genome multilocus sequence type as previous flour and clinical isolates associated with the outbreak. The result of this analysis demonstrates the potential for STEC to persist in wheat flour at levels associated with outbreak infections for periods of up to two years. This has implications for the potential for STEC to survive in other foods with low water activity.

中文翻译：

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产生志贺毒素的大肠杆菌在小麦粉中可以保存两年。

小麦粉最近被公认为是食源性病原体产志贺毒素的大肠杆菌（STEC）的暴露媒介。2016年10月在连续两个生产日研磨的小麦粉，涉及加拿大范围内STEC O121：H19的爆发，于2018年11月分析了STEC的存在。在室温下储存在密封容器中，各个面粉的水分活度样品在研磨后的6个月时低于0.5，并且在额外存储的18个月中单个样品保持静态或略有下降。分离出STEC O121，其基因型（stx2a，eae，hlyA）和核心基因组多基因座序列类型与以前与爆发相关的面粉和临床分离株相同。分析结果表明，STEC在小麦粉中以与爆发感染相关的水平持续长达两年的潜力。这对于STEC在低水分活度的其他食品中生存的潜力具有影响。