1. Laboratory for Antimicrobial Agents, Kitasato University, 5-9-1 Shirokane, Minato-Ku, Tokyo 108-8641, Japan
2. Isehara Research Laboratory, Kanto Chemical Co., Inc., 21 Suzukawa, Isehara, Kanagawa 259-1146, Japan
3. Graduate School for Infection Control Sciences, Kitasato University, 5-9-1 Shirokane, Minato-Ku, Tokyo 108-8641, Japan