Study On The Effects Of Bailalein Combined With Vancomycin On The Biofilm Of Satphylococcus Aureus In Rats

Objective: To study the effect of baicalein combined with vancomycin on biofilm infection of Staphylococcus aureus in rats by constructing an infection model of Staphylococcus aureus biofilm on the back of rats.Methods: The medical silica gel was used as the experimental carrier.Staphylococcus aureus(MRSA17546)was used as the experimental strain.The SD rats were randomly divided into four groups,namely the blank control group,baicalein group(100mg/kg),vancomycin Group(100 mg/kg),baicalein(100mg/kg)+ vancomycin group(100 mg/kg).After the establishment of the Staphylococcus aureus biofilm infection model on the back of the rat,the abdominal cavity administration method was used to inject the above drugs,and the blank control group was injected with the same amount of sterile physiological saline.Following 24 hours,48 hours and 72 hours after the drug was applied,the viable bacteria on the surface of the carrier were counted using a serial dilution method.The biofilm morphology on the surface of the carrier was observed by scanning electron microscopy.The local inflammatory tissue at the back pouch of the rat was stained with HE to observe local pathology and histology changes.Results: Staphylococcus aureus was cultured at 37°C for 72 hours to form a biofilm,and the vector was placed in the rat dorsal capsular bag to successfully construct a rat model of Staphylococcus aureus infection.After 48 hours of drug treatment,the surface colony counts of silica gel tablets in the concomitant drugs group or the single drug group were lower than those in the blank control group(P<0.05)and the drug use in vancomycin group was lower than that in the baicalein group(P<0.05);After 72 hours of drug treatment,baicalein +Vancomycin group was significantly reduced compared with baicalein group and vancomycin group(P<0.05).Scanning electron microscopy was used to observe the surface of the blank control group.It was found that the carrier bacteria in the blank control group formed a thicker biofilm than the single drug group and the concomitant drugs group;the vancomycin group was thinner than the baicalein group;the biofilm of the concomitant drugs group biofilm was basically destroyed,only a small amount of leukocyte adhesion was seen.In the control group,a large number of inflammatory cells infiltrated in the local inflammatory tissues,and exudation and hemorrhage were seen in the gross pathology.Compared with the blank control group,there was slight tissue damage in the single drug group,and local inflammatory cell infiltration was still seen in the microscope;the exudation of the vancomycin group was lower than that of the baicalein group;the concomitant drugs group showed less local exudation and hemorrhage and only few scattered inflammatory cells were observed.Conclusion: 1.The model of Staphylococcus aureus biofilm infection in rats can be successfully established.2.Baicalein alone can damage the Staphylococcus aureus biofilm established in rats.3.The application of baicalin and vancomycin could significantly enhance the bactericidal effect of vancomycin.4.Baicalein alone can reduce the inflammatory response of tissue,while combine vancomycin,the effect is more obvious.