Foodborne Outbreak of Extended Spectrum Beta-lactamase Producing Shigella sonnei Associated with Contaminated Spring Onions in the United Kingdom.

Globalization of the food supply chain has created conditions favorable for emergence and spread of multidrug-resistant (MDR) foodborne pathogens. In November 2021, the UK Health Security Agency detected an outbreak of 17 cases infected with the same strain of MDR extended spectrum beta-lactamase (ESBL)-producing Shigella sonnei. Phylogenetic analysis of whole-genome sequencing data revealed the outbreak was closely related to strains of S. sonnei isolated from travelers returning to the UK from Egypt. None of the outbreak cases reported travel and all 17 cases reported eating food from a restaurant/food outlet in the week prior to symptom onset, of which 11/17 (64.7%) ate at branches of the same national restaurant franchise. All 17 cases were adults and 14/17 (82.4%) were female. Ingredient-level analyses of the meals consumed by the cases identified spring onions as the common ingredient. Food chain investigations revealed that the spring onions served at the implicated restaurants could be traced back to a single Egyptian producer. The foodborne transmission of ESBL-producing bacteria is an emerging global health concern, and concerted action from all stakeholders is required to ensure an effective response to mitigate the risks to public health.

Outbreak of sexually transmitted, extensively drug-resistant Shigella sonnei in the UK, 2021-22: a descriptive epidemiological study.

BACKGROUND: Shigellosis, traditionally a foodborne and waterborne infection, causes substantial morbidity globally. It is now a leading cause of sexually transmitted gastroenteritis among gay, bisexual, and other men who have sex with men (MSM). We describe an ongoing outbreak of extensively drug-resistant (XDR) Shigella sonnei in the UK. METHODS: Routine laboratory surveillance (Second Generation Surveillance System, Gastrointestinal Data Warehouse) identified an exceedance of S sonnei clade 5 in England, first detected in September, 2021. Cases within this clade were subsequently reported from Scotland, Wales, and Northern Ireland. Confirmed cases in this outbreak were defined as individuals diagnosed with S sonnei clade 5 in the UK, with a specimen date between Sept 1, 2021, and Feb 9, 2022, who were genomically confirmed as part of a ten-single nucleotide polymorphism (SNP) linkage cluster. We used whole-genome sequencing with SNP typing to identify genomic clusters and antimicrobial-resistance determinants, analysing cases across the UK. We collected demographic, epidemiological, and clinical data from people infected with S sonnei clade 5 in England using questionnaires (standard and bespoke outbreak questionnaires). We used descriptive summary statistics to characterise cases. FINDINGS: 72 cases (70 [97%] male, median age 34 years [IQR 27-39]) belonging to the ten-SNP single linkage cluster of S sonnei clade 5 were identified between Sept 4, 2021, and Feb 9, 2022. Isolates were predominantly XDR, with 66 (92%) of 72 harbouring blaCTX-M-27, a plasmid-mediated gene for production of extended-spectrum ß-lactamases (ESBLs). Of 33 cases with clinical data, 19 (58%) received antibiotics and eight (24%) were hospitalised. 21 (78%) of 27 cases with completed bespoke outbreak questionnaires were HIV-negative MSM taking HIV pre-exposure prophylaxis (PrEP) who reported sexual contacts in the UK and Europe within the incubation period. INTERPRETATION: We highlight the rapid dissemination of XDR ESBL-producing S sonnei in sexual networks of MSM. We recommend strengthening shigella testing where clinically indicated, antimicrobial-resistance surveillance, and integrated health promotion messaging among all MSM, including PrEP users, to reduce the burden of shigellosis. FUNDING: National Institute for Health Research Health Protection Research Unit in Gastrointestinal Infections at the University of Liverpool in partnership with the UK Health Security Agency.