1. Department of Infectious Diseases, Keio University School of Medicine, Tokyo 160-8582, Japan
2. Department of Infectious Diseases, Graduate School of Medicine, International University of Health and Welfare, Narita 286-8520, Japan
3. Department of Microbiology, Tokyo Medical University, Tokyo 160-8402, Japan
4. Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8606, Japan
5. Department of Microbiology and Infectious Diseases, Nara Medical University, Nara 634-8522, Japan