1. Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
2. Department of Microbiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
3. Department of Pediatrics, KKR Sapporo Medical Center, Sapporo, Japan
4. Department of Pediatrics, Hokkaido Social Insurance Hospital, Sapporo, Japan
5. Department of Pediatrics, Sapporo Kosei General Hospital, Sapporo, Japan
6. Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, Japan
7. Pediatric Clinic, Touei Hospital, Sapporo, Japan