Study Of Baicalin In Combination With Meropenem On Pseudomonas Aeruginosa Early Biofilm In The Mouse Abdominal Cavity In Vivo

Objective : An experimental murine model of intra-abdominal infection with pseudomonas aeruginosa(P.a)early biofilm(BF)was used to observe the effect of Baicalin in combination with meropenem(MEM)on P.a early biofilm.Methods:With the infusion tube as the carrier,take the PAO1 wild strains as the experimental strains.32 female mice were randomly divided into 4groups:the blank control group,the baicalin group(60mg/Kg.d),the meropenem group(50mg/Kg.d)and the baicalin(60mg/Kg.d)+meropenem(50mg/Kg.d)group,8 mice in each group.After establishing the model of intra-abdominal infection,some of the mice were injected with the drugs above,the control group was injected with the same amount of sterile saline.Blood was drawn from heart after drug injection for 24 hours for enumeration of WBC count.The viable bacterial counts on the carriers' surface were determined by serial dilution.To observe the morphological changes of the BF on the surface of the carriers by means of scanning electron microscopy(SEM).Hematoxylin and eosin(HE)staining was performed for the observation of histological changes of local inflammatory tissue in abdominal cavity.Results:Pseudomonas aeruginosa was cultured for 20 h at 37? to form early BF.The carriers were implanted into the abdominal cavity of mice to establish the model of infection in vivo.The numbers of leukocytes of the baicalin group,the MEM group and the baicalin+MEM group were all less than those in the control group with drug application after 24 h(P<0.05);the wbc counts of the MEM group were less than the baicalin group(P<0.05);the wbc counts of the baicalin+MEM group were less than those in the baicalin group and the MEM group(P<0.05).Bacterial counts on the carriers' surface by using single drug or by using combined drugs were all less than those in the control group(P<0.01);bacterial counts of the MEM group were less than the baicalin group(P < 0.01);the viable colony counts of the baicalin+MEM group were significantly less than those in the baicalin group and MEM group(P <0.01).SEM revealed the BF formation of the control group were thicker than the baicalin group,MEM group and baicalin+MEM group;compared with the baicalin group,the MEM group formed thinner BF;the biofilms in the baicalin+MEM group were almost destroyed and cleared,only a small amount of P.a bacteria can be seen.The blank control group showed a lot of lymphocytes and macrophages infiltration in the inflammatory tissue,exudation and bleeding were also seen.Compared with the blank control group,tissue injury in the baicalin group and the meropenem group were more alleviated,but local inflammatory cell infiltration were still visible;exudate of the meropenem group reduced compared with the baicalin group;the structure of the baicalin+meropenem group was relatively clear,only a few scattered inflammatory cells were found.Conclusions:1?Baicalin can destroy the early biofilm of P.a in the mouse abdominal cavity;2?Meropenem can remove the early biofilm bacteria of P.a inthe mouse abdominal cavity;3?Baicalin can obviously enhance the bactericidal activities on biofilm in combination with meropenem.