Isolation And Identification Of Pasteurella Bovis And The Therapeutic Effect Of Baicalin On Pasteurella Pneumonia

Pasteurella multocida is a pathogenic microorganism that causes a variety of serious diseases in human and animals worldwide and cause serious economic losses to the global breeding industry.The pathogenic bacteria not only causes disease in animals but also human.Therefore,the bacterium is also one of the primary pathogens that endanger the safety of humans.There are many serotypes of Pasteurella multocida,and the cross protection between different capsilar serotypes is not well.In the treatment of this disease,commonly used antibiotics are selected for long time,so that the bovine Pasteurella multocida performance for high resistance rate,resistance range,multi-drug resistance and other characteristics,While the residues of antibiotics in the animal body to cause some harm to animal and human.Therefore,there is a clinical need drugs to replace antibiotics that is low-toxic,effective and antibacterial residue-free.It is confirmed that herbal medicines can directly inhibit or kill pathogenic bacteria and do not produce drug resistance.Herbal medicines have become a popular direction for the treatment of animal clinical diseases.In this experiment,pathogenic bacteria were isolated from the diseased dead bovine lungs from three dairy farms in Shaanxi Province.and bacterial identification and biological characterization were tested.The test strains were selected by drug sensitivity tests.Inhibition tests in vitro and MIC measurements were performed to screen out 20 Chinese herbal medicines with good inhibition effect on multi-drug resistant strains.The multi-drug resistant strains were used for nasal drops infection and establishment mouse pneumonia model,and the therapeutic effect of Baicalin that is main component of Scutellaria baicalensis was tested.The main results as follows.1.Three etiological strains(P1,P2,P3)were isolated.The orphological observation,biochemical identification,16S r RNA gene sequencing,specific gene and podoconjugate serotype-specific gene identification were performed to the isolates.The results showed that all 3 strains were Pasteurella multocida capsular serotype A.The 3 strains had similar growth patterns under the same conditions and were all pathogenic.2.P3 was sensitive to all 16 drugs;P1 and P2 were resistant toβ-amides(cefuroxime,cefotaxime,ampicillin,penicillin)、sulfonamides(methicillin)and quinolones(ofloxacin).The results indicating that P1 and P2 were multi-drug resistant strains.Pasteurella multocida P1,P2 and P3 were highly sensitive to eight Chinese herbal medicines:Ocimum sanctum,Turbinicarpus,Pomegranate bark,Schisandra chinensis,Scutellaria baicalensis,Rhubarb,Mugwort and Schisandra chinensis.Scutellaria baicalensis had the smallest minimum inhibitory concentration value(1.95 mg/m L)and the best inhibitory effect.3.A mouse pneumonia model was established by intranasal induction with 20μL(10~6CFU/m L)of Pasteurella multocida.The peripheral serum leukocyte count,ghrelin,interleukin1β(IL-1β),interleukin 6(IL-6),tumor necrosis factor-α(TNF-α),and C-reactive protein(CRP)were significantly elevated.There were abnormal alveolar structures,erythrocytes in the alveolar lumen,inflammatory cell infiltration,and thickened alveolar septa.Treatment with baicalin reduced the peripheral serum leukocyte count,ghrelin,IL-1β,IL-6,and TNF-αin mice,while the lung lesions were significantly improved with less inflammatory cells and erythrocyte infiltration in the alveolar cavity,demonstrating that the inflammatory response of mouse lung tissue was attenuated.