Study On The Inhibitory Effect Of Essential Oil Of Cinnamomum Camphora On Biofilm Of Dairy Endometritis E.coli

Dairy cow endometritis is a postpartum disease in dairy cows that can lead to infertility.It is one of the three major diseases that endanger the dairy industry.The main cause of endometritis in dairy cows is the infection of pathogenic microorganisms,such as Escherichia coli,Cryptocaryon occlusions,Staphylococcus aureus,Bacillus cereus,Candida albicans and so on.Due to the long-term reliance on antibiotics for the treatment of cow endometritis,bacterial resistance is enhanced.Biofilms play an important role in bacterial colonization,infection and the acquisition and spread of bacterial resistance.Therefore,biofilms are the target of anti-infective therapy and have become an effective way to screen and discover new antibacterial drugs.In recent years,more and more studies have been conducted on the inhibition of bacterial biofilms by traditional Chinese medicines.The essential oils have strong permeability and have a broad-spectrum anti-microbial effect,which has attracted the attention of researchers.In this study,firstly,single factor method and response surface optimization method were used to optimize the culture conditions of E.coli biofilms.Secondly,the biofilm phenotype of E.coli isolated from clinical endometritis of dairy cows was examined.The phenotypes of biofilms were analyzed.The relevance of murine pathogenicity was finally evaluated for the inhibitory effect of camphor essential oil on E.coli biofilm.The main results of the experiment are as follows:1 The response surface(RSM)analysis optimized the culture conditions of E.coli ATCC25922 biofilm: bacterial concentration 1.2×107 cfu/ml,p H 7.0,time 11.5 h,E.coli biofilm OD value 0.605,optimized OD The value of OD increased by about 0.4 compared to the condition without optimization.2 Biofilm capacity of 44 clinical isolates of E.coli isolates from dairy cows was tested,of which 22 strains(50%)were strains with strong biofilm formation capacity and lethality to mice.It was 53.03%;9 strains(20.45%)were strains with intermediate biofilm formation capacity,and the lethal rate to mice was 51.85%;8 strains(18.18%)were strains with weak biofilm formation ability to mice.The lethality rate was 42.83%;5 strains(11.36%)were strains with no biofilm formation capacity,and the lethality rate to mice was 20%.3 The antibacterial concentration of camphor essential oil against clinical E.coli isolates is 5,903 ?l/ml,90% antibacterial,4.297 ?l/ml,50% bactericidal concentration,3.870 ?l/ml,and 90% bactericidal concentration 6.378 ?l/ml,50% inhibition concentration for the biofilm of clinical isolates of E.coli was 3.619 ?l/ml,90% inhibition concentration was 6.850 ?l/ml,50% bactericidal concentration was 4.693 ?l/ml,and 90% bactericidal concentration was 8.467 ?l/ml.Scanning electron microscopy and laser confocal microscopy were used to directly observe the significant inhibitory effect of Toona sinensis oil on the number and morphology of E.coli biofilms.