Objective To study the in vitro antibacterial activity of meropenem combined with doxycycline, ciprofloxacin, sulbactam or cefoperazone/sulbactam against clinically isolated extensively drug-resistant Acinetobacter baumannii (XDRAB). Methods Using a checker board synergy design, the minimal inhibitory concentration (MIC) of antibiotics against 50 isolates of XDRAB was determined by broth microdilution antifungal susceptibility test. The fractional inhibitory concentration (FIC) index was calculated to determine the combined effect of the antibiotics. Results Meropenem showed significantly reduced MIC50 and enhanced antimicrobial activities when combined with doxycycline, sulbactam or cefoperazone/sulbactam. The FIC results suggested that the main actions of doxycycline, sulbactam, and cefoperazone/sulbactam were synergistic (38%, 26%, and 10%, respectively) and addictive (62%, 74%, and 90%, respectively) without indifferent or antagonistic effects. The main actions of meropenem combined with ciprofloxacin were additive (56%) and indifference (44%) with synergistic and antagonistic effects. Conclusion Meropenem combined with doxycycline, sulbactam or cefoperazone/sulbactam shows excellent activity against clinical isolates of XDRAB.%目的：评价美罗培南与多西环素、环丙沙星、舒巴坦及头孢哌酮/舒巴坦联合用药对泛耐药鲍曼不动杆菌的体外抗菌效应。方法采用棋盘法设计，微量肉汤稀释法测定不同浓度组合的抗菌药物对50株临床分离的泛耐药鲍曼不动杆菌的最低抑菌浓度，并计算部分抑菌浓度（FIC）指数判定联合效应。结果美罗培南与多西环素联用后，其MIC50显著下降，FIC指数分布：FIC≤0.5占38%，0.52为0。美罗培南与环丙沙星联用后，其MIC50下降不明显，FIC指数分布：FIC≤0.5为0，0.52为0。美罗培南与舒巴坦联用后，其MIC50明显下降，FIC指数分布：FIC≤0.5为26%，0.52为0。美罗培南与头孢哌酮/舒巴坦联用后，其MIC50有所下降，FIC指数分布：FIC≤0.5为10%，0.52为0。结论美罗培南与多西环素、舒巴坦或者头孢哌酮/舒巴坦联合，对泛耐药鲍曼不动杆菌均表现为协同和相加作用，没有无关作用和拮抗作用，具有良好的体外抗菌活性；而美罗培南与环丙沙星联合表现出的相加作用和无关作用比例相当，对泛耐药鲍曼不动杆菌的体外抗菌活性较差。
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