1. Department of Microbiology; University of Occupational and Environmental Health; 1-1 Iseigaoka, Yahatanishi-ku Kitakyushu 807-8555 Japan
2. Department of Environmental Management 1; University of Occupational and Environmental Health; 1-1 Iseigaoka, Yahatanishiku Kitakyushu 807-8555 Japan
3. Department of Bacteriology, Graduate School of Medical Sciences; Kyushu University; 3-1-1 Maidashi, Higashiku Fukuoka 812-8582 Japan
4. Department of Microbiology, College of Physicians and Surgeons; Columbia University; 701 West 168th Street New York NY 10032