encoding Shiga toxin subtype Stx2f causing human infections in England, 2015-2022.

Shiga toxin-producing (STEC) belong to a diverse group of gastrointestinal pathogens defined by the presence of Shiga toxin genes () of which there are at least ten subtypes (Stx1a-Stx1d and Stx2a-Stx2g). Initially thought to be associated with mild symptoms, more recently STEC encoding have been isolated from cases of haemolytic uraemic syndrome (HUS) and the clinical significance and public health burden require further investigation. We analysed clinical outcomes and genome-sequencing data linked to patients infected with STEC encoding- in England to assess the risk to public health. One hundred and twelve (=58 isolates encoded ; =54 isolates belonging to CC122 or CC722 that had but were negative for ) isolated from patients' faecal specimens between 2015 and 2022 were genome sequenced and linked to epidemiological and clinical outcome data. All isolates were investigated for the presence of virulence genes and a maximum-likelihood phylogeny of isolates belonging to CC122 and CC722 was constructed. There were 52 cases infected with STEC harbouring between 2015 and 2022, with the majority identified in 2022. Most cases resided in the North of England (=39/52, 75 %), were female (=31, 59.6 %) and/or aged five and under (=29, 55.8 %). Clinical outcome data were available for 40/52 cases (76.9 %) and 7/40(17.5 %) were diagnosed with STEC-HUS. In the two most common clonal complexes, CC122 and CC722, the presence of the -encoding prophage correlated with the presence of additional virulence genes, and , located on an 85kbp IncFIB plasmid. Certain serotypes of harbouring cause severe clinical outcomes, including STEC-HUS. Public health advice and possible interventions are limited, as little is known about the animal and environmental reservoirs and transmission routes. We recommend more comprehensive and standardized collection of microbiological and epidemiological data, and routine sharing of sequencing data between public health agencies worldwide.