1. Department of Animal and Grassland Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan
2. Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
3. Division of Bacteriology, Osaka Prefectural Institute of Public Health, Osaka, Japan
4. Department of Microbiology Infection Control, Statens Serum Institut, Copenhagen, Denmark
5. WHO Collaborating Centre for Reference and Research on Escherichia and Klebsiella, Statens Serum Institut, Copenhagen, Denmark