1. Department of Internal Medicine, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan
2. Department of Infection Control and Prevention, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan
3. Tokyo Gakugei University Health Service Center, 4-1-1 Nukuikita-machi, Koganei, Tokyo 184-8501, Japan
4. Yaizu City Hospital, Dobara 1000, Yaizu, Shizuoka 425-8505, Japan