1. Laboratory of Enteric Pathogens, Specialist and Reference Microbiology Division, Health Protection Agency, London NW9 5HT, UK
2. Department of Endoscopy and Gastrointestinal Endoscopy, National Cancer Centre Hospital, Tokyo 104-0045, Japan
3. The Centre for Digestive Diseases, The General Infirmary at Leeds, Leeds LS1 3EX, UK
4. Health Protection Agency Laboratory, York Road, Leeds LS15 7TR, UK