In Vitro And Vivo Activities Of Imipenem In Combination With Other Antibiotics Against The Strains Of Pandrug Resistant Acinetobater Baumannii

Objective: To observe the combination of Imipenem,Polymyxin B,Rifamycinand minocycline and so on against Acinetobater baumannii(Ab) in vitro and in vivo ,and then to investigate clinical medication. Methods: 20 strains of Acinetobater baumannii and Escherichia coli ATCC 25922,Pseudomonas Aeruginosa ATCC27853were used in vitro.FIC indices were calculated by the simplified chequerboard method to evaluate the interactions between two of them against Acinetobater baumannii . In vivo , to construct a neutropenic mouse pneumonia model,caused by pandrug resistant Acinetobater baumannii. Treatment by combined antibiotic .Survival time,the degree of inflammation in lung tissue,and bacterial colony counting were observed for the evaluation of antibiotic interactions.Results:In vitro, the combined sensitivity test to 20 strains of Acinetobater baumannii , Imipenem and Piperacillin-tazobactam combined synergy of 30%, Imipenem and Minocycline combined synergy of 55%, Imipenem and rifamycin combined synergy of65%,Imipenem and Polymyxin B combined synergy of 60%. Construction a mouse pneumonia model successfully, caused by pandrug resistant Acinetobater baumannii. This pneumonia model results show: 1.Polymyxin B was the only monotherapy regimen that significantly reduced the bacterial load in lungs compared with the control post-infection(P<0.05)and bactericidal(≥3△lg CFU·mL-1),at 24h and 48h. 2. the combination of Imipenem and Polymyxin B was bactericidal(at 24h and 48h) and synergistic(at 48h);Combining Imipenem treatment with one of Rifamycin , Minocycline and Piperacillin-tazobactam were bactericidal and synergistic at 48h。Imipenem and Sulbactam was not different。Conclusion: Imipenem combination of Minocycline,Polymyxin B, Piperacillin-tazobactam and Rifamycin in vitro ,showed synergistic30%,at least.Except of Imipenem and Sulbactam, the combination of them were synergistic in vivo.