Outbreak of Shiga toxin-producing Escherichia coli O157 linked with consumption of a fast-food product containing imported cucumbers, United Kingdom, August 2020

Background: In August 2020, an outbreak of Shiga toxin-producing Escherichia coli (STEC) O157:H7 occurred in the United Kingdom. Whole genome sequencing revealed that these cases formed a genetically distinct cluster. Methods: Hypotheses generated from case interviews were tested in analytical studies, and results informed environmental sampling and food chain analysis. A case-case study used non-outbreak 'comparison' STEC cases; a case-control study used a market research panel to recruit controls. Results: A total of 36 cases were identified; all cases reported symptom onset between August 3 and August 16, 2020. The majority of cases (83%) resided in the Midlands region of England and in Wales. A high proportion of cases reported eating out, with one fast-food restaurant chain mentioned by 64% (n = 23) of cases. Both the case-case study (adjusted odds ratio (aOR) 31.8, 95% confidence interval (CI) 1.6-624.9) and the case-control study (aOR 9.19, 95% CI 1.0-82.8) revealed statistically significant results, showing that the consumption of a specific fast-food product was independently associated with infection. Conclusions: Consumption of a specific fast-food product was a likely cause of this outbreak. The only ingredient specific to the product was cucumbers. The supply of cucumbers was immediately halted, and no further cases have been identified. (C) 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.

Automated summary

An outbreak of STEC O157:H7 occurred in the UK in August 2020, linked to the consumption of a specific fast-food product, mainly affecting cases in the Midlands and Wales; case-case and case-control studies revealed statistically significant associations of the outbreak with the consumption of this product, leading to immediate cessation of cucumber supply and containment of the outbreak.