1. Laboratory of Veterinary Public Health, School of Veterinary Medicine and Animal Sciences, Kitasato University, Higashi 23-35-1, Towada Aomori 034-8628
2. Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871
3. Faculty of Pharmaceutical Sciences, Okayama University, Tsushima-Naka, Okayama 700-8530
4. Department of Laboratory Medicine, Kurashiki Central Hospital, Kurashiki, Okayama 710-8602, Japan