1. School of Nursing; Jichi Medical School; Tochigi 329-0481 Japan
2. Department of Bacteriology; The Jikei University School of Medicine; Minato-ku Tokyo 105-0003 Japan
3. Department of Clinical Pathology; Jichi Medical School; Tochigi 329-0481 Japan
4. Department of Bacteriology; Kitazato University; Sagamihara Kanagawa 228-8555 Japan
5. Department of Pediatrics; Jichi Medical School; Tochigi 329-0481 Japan
6. Department of Microbiology; Jichi Medical School; Tochigi 329-0481 Japan