1. Department of Oral Microbe Control, Graduate School of Medicine, Osaka University, Osaka, Japan.
2. Department of Infection Control and Prevention, Graduate School of Medicine, Osaka University, Osaka, Japan.
3. Department of Infectious Diseases, Osaka City General Hospital, Osaka, Japan.
4. Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan.
5. Rinku General Medical Center, Osaka, Japan.
6. Yokohama Municipal Citizen's Hospital, Kanagawa, Japan.
7. Tokyo Metropolitan Bokutoh Hospital, Tokyo, Japan.
8. Sapporo City General Hospital, Sapporo, Japan.