[1] Barts Hlth NHS Trust, Dept Resp Med, London, England
[2] Barts Hlth NHS Trust, Royal London Hosp, Dept Gastroenterol, London, England
[3] Queen Mary Univ London, Blizard Inst, Natl Ctr Bowel Res, London, England
[4] Queen Mary Univ London, Blizard Inst, Barts & London Sch Med & Dent, 4 Newark St, London E1 2AT, England
[5] Barts Hlth NHS Trust, Royal London Hosp, Dept Infect Dis, London, England
[6] Barts Hlth NHS Trust, Royal London Hosp, Dept Pathol, London, England