1 Department of Gastroenterology, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-8655, Japan.
2 Department of Gastroenterology, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-8655, Japan. ytsujitky@g.ecc.u-tokyo.ac.jp.
3 Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1, Hongo, Tokyo, 113-8655, Japan. ytsujitky@g.ecc.u-tokyo.ac.jp.
4 Department of Endoscopy and Endoscopic Surgery, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-8655, Japan.
5 Center for Epidemiology and Preventive Medicine, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-8655, Japan.
6 Center for International Preventive Medicine, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-8655, Japan.
7 Infection Control and Prevention Service, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-8655, Japan.