Antimicrobial agents
Nacubactam hydrate was provided by Meiji Seika Pharma Co., Ltd. (Tokyo, Japan). Aztreonam powder (Tokyo Chemical Industry Co., Ltd., Tokyo, Japan) and aztreonam 1.0 g vials (Eisai Co., Ltd., Tokyo, Japan) were used for in vitro study, including a standard for concentration analysis and in vivo study, respectively.