A series of fused bicyclic 2-aminothiazolyl compounds were synthesized and evaluated for their synergistic effects with polymyxin B (PB) against Klebsiella pneumoniae (SIPI-KPN-1712). Some of the synthesized compounds exhibited synergistic activity. When 4 μg ml⁻¹ compound B1 was combined with PB, it showed potent antibacterial activity, achieving 64-fold reduction of the MIC of PB. Furthermore, compound B1 showed prominent synergistic efficacy in both concentration gradient and time-kill curves in vitro. In addition, B1 combined with PB also exhibited synergistic and partial synergistic effect against E. coli (ATCC25922 and its clinical isolates), Acinetobacter baumannii (ATCC19606 and its clinical isolates), and Pseudomonas aeruginosa (Pae-1399).

中文翻译：

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稠合双环2-氨基噻唑基化合物与多粘菌素B对抗肺炎克雷伯菌的协同作用

合成了一系列稠合的双环2-氨基噻唑基化合物，并评估了它们与多粘菌素B（PB）对肺炎克雷伯菌的协同作用（SIPI-KPN-1712）。一些合成的化合物表现出协同活性。当将4μgml ^-1的化合物B1与PB结合时，它显示出强大的抗菌活性，使PB的MIC降低了64倍。此外，化合物B1在体外浓度梯度和时间杀灭曲线中均显示出显着的协同功效。此外，B1与PB结合还对大肠杆菌表现出了协同和部分协同作用（ATCC25922及其临床分离株），鲍曼不动杆菌（ATCC19606及其临床分离株）和铜绿假单胞菌（Pae-1399）。