1. Department of Pediatrics, Asahi General Hospital, 1326 I, Asahi, Chiba 289-2511, Japan
2. Department of Emergency and Critical Care Medicine, Aizawa Hospital, 2-5-1 Honjo, Matsumoto, Nagano 390-8510, Japan
3. Department of Clinical Laboratory, Asahi General Hospital, 1326 I, Asahi, Chiba 289-2511, Japan
4. Division of Bacteriology, Chiba Prefectural Institute of Public Health, 666-2 Nitona, Chuo, Chiba 260-8715, Japan