1. Gastrointestinal Bacteria Reference Unit, Public Health England, Colindale, London, United Kingdom
2. Statistics, Modelling and Economics Department, Public Health England, Colindale, United Kingdom
3. Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, United Kingdom
4. Scottish Salmonella, Shigella and Clostridium difficile Reference Laboratory, Glasgow, United Kingdom
5. Microbiology, Norwich and Norfolk University hospital and the Norwich Medical School, University of East Anglia, Norfolk, United Kingdom
6. Clinical Infection, Microbiology and Immunology, University of Liverpool, United Kingdom