1 Department of Infectious Diseases The University of Tokyo Hospital Tokyo, Japan Department of Infectious Diseases The University of Tokyo Hospital Tokyo, Japan kokamoto-tky@umin.ac.jp Department of Infectious Diseases The University of Tokyo Hospital Tokyo, Japan Departments of Infectious Diseases and Infection Control and Prevention The University of Tokyo Hospital Tokyo, Japan Department of Gastroenterology The University of Tokyo Hospital Tokyo, Japan Department of Infection Control and Prevention The University of Tokyo Hospital Tokyo, Japan Department of Infectious Diseases The University of Tokyo Hospital Tokyo, Japan Department of Gastroenterology The University of Tokyo Hospital Tokyo, Japan Departments of Infectious Diseases and Infection Control and Prevention The University of Tokyo Hospital Tokyo, Japan.