1. Department of Bacteriology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
2. Nagoya City Public Health Research Institute, Nagoya, Japan.
3. Department of Microbiology, Nagoya City University Hospital, Nagoya, Japan.
4. Department of Microbiology and Medical Zoology, Aichi Prefectural Institute of Public Health, Nagoya, Japan.