Outbreak of Salmonella enteritidis PT14b gastroenteritis at a restaurant in England: the use of molecular typing to achieve a successful prosecution

- Fifteen cases of Salmonella enteritidis had the same multiple locus variable-number tandem repeat analysis (MLVA) profile as environmental and food samples collected from an implicated restaurant.
- Adenosine triphosphate hygiene swab tests and data loggers provided evidence of poor quality cleaning procedures.
- Robust epidemiological, microbiological and environmental investigations, including the use of molecular typing led to the successful prosecution of the food business operator.

ObjectivesTo describe an outbreak of Salmonella enteritidis phage type (PT) 14b in people who had eaten at a restaurant, and the investigation and subsequent prosecution of the food business operator (FBO).Study designThe local health protection team and environmental health department formed an outbreak control team to investigate the outbreak.MethodsEpidemiological, microbiological, and environmental investigations were undertaken. Epidemiological investigations involved case finding and interviews. Microbiological investigation: stool samples from the suspected cases and environmental samples from the implicated food business were investigated. Salmonella isolates obtained were subjected to multiple locus variable-number tandem repeat analysis (MLVA) profiling and whole genome sequencing. In addition, adenosine triphosphate (ATP) hygiene swab tests were used to verify the quality of cleaning procedures and data loggers were used to determine the water temperature of the mechanical dishwasher.ResultsFifteen cases of illness where the causative agent was shown to be S. enteritidis PT14b were identified, all of whom had eaten at the same restaurant. S. enteritidis PT14b was also identified from three of the 11 food and environmental samples taken at the restaurant and found to have the same MLVA profile as the cases. A case for prosecution was built and the FBO was successfully prosecuted in July 2015.ConclusionsThis investigation highlighted that the use of molecular typing as part of thorough epidemiological, microbiological, and environmental investigations can present a robust case for prosecution against restaurants which pose a risk to public health.