异丙氧苯胍与黏菌素联用对多杀性巴氏杆菌的体内外抗菌作用

In vitro and in vivo Antibacterial Effect of Isopropoxy Benzene Guanidine Combined with Colistin Against Pasteurella multocida

[目的]研究异丙氧苯胍与黏菌素联用对多杀性巴氏杆菌的体内外抗菌作用,为开发有效的新型黏菌素增效剂及临床防治多杀性巴氏杆菌病提供数据支持。[方法]通过微量肉汤稀释法测定异丙氧苯胍与黏菌素对多杀性巴氏杆菌的最小抑菌浓度,再通过棋盘法联合药敏试验和时间杀菌曲线评价异丙氧苯胍与黏菌素联用对多杀性巴氏杆菌的体外抗菌作用,并进一步通过建立小鼠肺部感染多杀性巴氏杆菌模型来评价两者联用的体内抗菌效果。[结果]药敏试验结果显示,异丙氧苯胍对多杀性巴氏杆菌无抗菌作用(MIC>256μg/mL),黏菌素对受试菌株的最小抑菌浓度范围为1~8μg/mL。联合药敏试验结果显示,异丙氧苯胍与黏菌素联用时能增强黏菌素的抗菌活性(分级抑菌浓度指数在0.094~0.313),表现出良好的协同抗菌作用。体外时间杀菌曲线结果进一步表明,联合用药组可显著降低细菌数量,当亚抑菌浓度(0.5μg/mL)的黏菌素与异丙氧苯胍联用时即可达到杀菌效果。在小鼠肺部感染模型中,与黏菌素或异丙氧苯胍单药组相比,异丙氧苯胍与黏菌素联合组能显著或极显著降低小鼠肺部多杀性巴氏杆菌的载菌量(P<0.05或P<0.01)。HE染色观察小鼠肺脏病理组织切片发现,异丙氧苯胍与黏菌素联合组小鼠肺脏的肺泡结构正常,肺泡腔清洁,优于异丙氧苯胍和黏菌素单独用药组。[结论]异丙氧苯胍与黏菌素联合使用可增强黏菌素对多杀性巴氏杆菌的体内外抗菌效果,有望进一步开发成为新型抗菌增效剂。

[Objective]This study was aimed to investigate the antibacterial effect of isopropoxy benzene guanidine(IBG)with colistin against Pasteurella multocida(P.multocida)in vivo and in vitro,in order to provide data support for the development of effective new colistin synergists and clinical prevention and treatment of P.multocida.[Method]The minimum inhibitory concentration of IBG and colistin was determined by broth microdilution.The in vitro antibacterial activity against P.multocida was evaluated by checkerboard assays and time-kill curves,and the in vivo antibacterial effect was further evaluated by establishing a mouse lung infection model.[Result]The drug sensitivity test results showed that IBG had no antibacterial effect on P.multocida(MIC>256μg/mL),the MIC range of colistin on the tested P.multocida strains was 1-8μg/mL.When IBG was combined with colistin,it could enhance the antibacterial activity of colistin(FIC was 0.094-0.313),demonstrating an excellent synergistic antibacterial effect.The time-kill curves further indicated that the combination group could significantly reduce the number of bacteria.The bactericidal effect could be achieved when colistin with sub inhibitory concentration(0.5μg/mL)was combined with IBG.In the mouse lung infection model,the combination group could significantly or extremely significantly reduce the bacterial burden of P.multocida in lungs compared to the colistin or IBG alone group(P<0.05 or P<0.01).The pathological tissue sections of mouse lungs showed that the alveolar structure was normal and the alveolar cavities were clean in the combined group,which was better than IBG and colistin alone.[Conclusion]The combination of IBG and colistin could enhance the antibacterial effect of colistin against P.multocida in vivo and in vitro,and was expected to be further developed as a new antibacterial synergist.