1. Primary Care Unit; Health Protection Agency, Gloucestershire Royal Hospital; Gloucester; UK
2. Endoscopy Unit; Gloucestershire Hospitals NHS Foundation Trust; Gloucester; UK
3. Statistics Unit; Health Protection Agency; London; UK
4. Public Health Wales Microbiology Bangor; Ysbyty Gwynedd; Bangor; UK
5. Helicobacter Reference Unit; Laboratory of Gastrointestinal Pathogens, HPA; London; UK
6. Institute of Medical Microbiology and Hygiene; University Hospital Freiburg; Freiburg; Germany