1. 1Public Health England North East Health Protection Team, New castle, UK
2. 2Public Health England Field Epidemiology Service, New castle, UK
3. 3Public Health England Food, Water and Environmental Microbiology Laboratory, York, UK
4. 4Durham District Council Food Safety, Durham, UK
5. 5Public Health England Gastrointestinal Bacteria Reference Unit, Colindale, London, UK
6. 6Stockton-on-Tees District Council Environmental Health, Stockton-on-Tees, UK