1. Division of Microbiology and Infectious Diseases, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
2. Center for Advanced Oral Science, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
3. Division of Periodontology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
4. Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan