12a - Shiga toxin–producing Escherichia coli (STEC) O145:H28 outbreak linked to pre-packaged sandwiches in the UK, 2024
Fireside Abstracts
Information
Background : Shiga toxin-producing Escherichia coli (STEC) is of public health concern due to the potential severity of illness, including sequalae such as Haemolytic Uraemic Syndrome (HUS). Non-O157 STEC serogroups cause large outbreaks of high severity. In May 2024 national gastrointestinal infections surveillance identified a fast-growing outbreak of STEC O145:H28 in England and Scotland.
Methods : Confirmed cases across the UK were identified through routine whole genome sequencing. Routine surveillance questionnaires were used for descriptive analysis. A case-case study was undertaken for hypothesis generation using confirmed cases and non-outbreak English STEC cases. Hypotheses were tested using data from trawling questionnaires in an analytical case-control study. Market panel controls were recruited, frequency matched on age. Concurrent food-chain and microbiological investigations were undertaken.
Results : There were 291 confirmed cases, with symptom-onset between 29/04/2024-16/08/2024; 58% of cases were female, the median age was 29 years (range 1-89 years), with 79% reporting bloody diarrhoea and 49% admitted to hospital. Nine cases developed HUS and two cases died. Case-case analysis identified pre-packaged sandwiches as a risk factor (OR=4.91, 95% CI=1.51-15.1, p=0.004).In the case-control study, eating a pre-packaged sandwich containing lettuce was identified as being associated with being a case (aOR=7.1, 95% CI=3.0-17.5, p < 0.05). Food chain investigations identified a lettuce product and a recall of affected products was initiated on 13/06/2024.
Conclusions : We report one of the largest outbreaks of STEC in the UK and demonstrate non-O157 STEC can cause clinically severe disease. Multiagency investigations led to rapid implementation of control measures. The risks associated with ready-to-eat products are highlighted, as well as the importance of effective control measures by manufacturers where the consumers are unable to implement risk mitigation.
