1. Department of Bacteriology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
2. Antimicrobial Resistance Research Center, National Institute of Infectious Diseases, Higashimurayama, Tokyo, Japan
3. Faculty of Medicine, School of Medicine, Gunma University, Maebashi, Gunma, Japan
4. Laboratory of Bacterial Drug Resistance, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan