亚胺培南联合磷霉素对多重耐药鲍曼不动杆菌的试验研究

目的 探索以亚胺培南为基础用药，对临床分离多重耐药鲍曼不动杆菌(MDR-AB)的体内外抗菌方法。方法 用微量肉汤稀释法及棋盘法测定7株临床分离的MDR-AB对亚胺培南、磷霉素、阿米卡星、替加环素、多粘菌素B 5种抗菌药物的最低抑菌浓度(MIC)及联合MIC,并计算部分抑菌浓度指数(FICI)。用时间杀菌曲线法判断亚胺培南联合磷霉素的杀菌效果。选取菌株AB6624、AB0153构建体外生物膜模型，结晶紫染色法半定量生物膜。激光共聚焦显微镜观察使用亚胺培南联合磷霉素对生物膜细菌的杀伤作用。流式细胞仪检测亚胺培南及磷霉素单药与联合用药对细菌活性氧(ROS)表达的影响。建立大蜡螟感染模型，记录亚胺培南及磷霉素单药与联合用药时大蜡螟存活率。结果 亚胺培南联合磷霉素对5株MDR-AB具有协同作用；亚胺培南联合磷霉素对菌株AB6624、AB0153分别在4、8 h的菌落数较单药组降低>2log₁₀ CFU/mL;亚胺培南联合磷霉素抑制菌株生物膜形成并对菌株AB0153生物膜结构具有破坏作用；亚胺培南联合磷霉素可以提高菌株AB0153胞内ROS水平，差异具有统计学意义(P&...

Effect of imipenem combined with fosfomycin on multidrug-resistant Acinetobacter baumannii

Objective To explore imipenem-based in vitro and in vivo antibacterial methods against clinically isolated multidrug-resistant Acinetobacter baumannii (MDR-AB). Methods The minimal inhibitory concentrations (MICs) and combined MICs of seven clinically isolated MDR-AB strains against 5 antimicrobial agents (imipenem ［IMP］, fosfomycin ［FOS］, amikacin ［AMI］, tigecycline ［TGC］, and polymyxin B ［PB］) were detected using broth microdilution and checkerboard methods. Fractional inhibitory concentration index (FICI) was calculated. Bactericidal effect of imipenem combined with fosfomycin was determined by time-bactericidal curve. The strains AB6624 and AB0153 were selected to construct the in vitro biofilm model, and biofilm was semi-quantitatively detected by crystal violet staining. Killing effect of imipenem combined with fosfomycin on biofilm bacteria was observed with laser scanning confocal microscopy. Effects of imipenem alone or in combination with fosfomycin on bacterial reactive oxygen species expression were detected by flow cytometry. Wax moth infection model was constructed, and survival rates of wax moth treated with imipenem and fosfomycin alone or in combination were recorded. Results Imipenem combined with fosfomycin had synergistic effect on 5 MDR-AB strains. After combined treatment of imipenem and fosfomycin, colony numbers of AB6624 and AB0153 at 4 and 8 hour were lower than those with single-drug-treatment group by more than 2log₁₀ CFU/mL. The combined use of imipenem and fosfomycin inhibited the formation of AB0153 biofilm and destroyed its structure. It also increased the intracellular ROS level in AB0153, with statistically significant difference (P<0.05). Compared with control group, imipenem combined with fosfomycin treatment group improved the survival rate of wax moth (median survival time 96 hours), with statistically significant difference (P=0.022). Conclusion Imipenem combined with fosfomycin has synergistic effect on MDR-AB, and may play a role by inhibiting biofilm formation and increasing intracellular ROS level of bacteria.