1. Department of Infectious Diseases; Tokyo Women's Medical University School of Medicine; Shinjuku-ku Tokyo 162-8666 Japan
2. Central Clinical Laboratory; Tokyo Women's Medical University School of Medicine; Shinjuku-ku Tokyo 162-8666 Japan
3. Department of Microbiology and Immunology; Tokyo Women's Medical University School of Medicine; Shinjuku-ku Tokyo 162-8666 Japan