[1] Univ Nottingham Hosp, Wolfson Digest Dis Fdn, Queens Med Ctr, Nottingham NG7 2UH, England
[2] Royal Hallamshire Hosp, Dept Gastroenterol, Sheffield, S Yorkshire, England
[3] Derby City Gen Hosp, Dept Gastroenterol, Derby, England
[4] Univ Nottingham Hosp, Div Microbiol, Queens Med Ctr, Nottingham NG7 2UH, England
[5] Univ Nottingham Hosp, Div Histopathol, Queens Med Ctr, Nottingham NG7 2UH, England
[6] Univ Nottingham Hosp, Div Epidemiol & Publ Hlth, Queens Med Ctr, Nottingham NG7 2UH, England