Study On Antimicrobial Activity And Mechanism Of Eugenol Against Multi-drug Resistant Escherichia Coli

In recent years,due to the abuse of antibiotics,the problem of multiple drug resistance of bacteria has become increasingly prominent,resulting in fewer and fewer antibiotics that can effectively treat bacterial diseases in clinic.Therefore,it is particularly urgent to find new effective bacteriostatic substances.Since traditional Chinese medicine has the advantages of less resistance,less side effects and obvious efficacy,traditional Chinese medicine has become one of the important sources of plant-derived bacteriostat.In this study,multi-drug resistantEscherichia coli?MDR E.coli?isolated from clinic was chosen as the research object.Traditional Chinese medicine with obvious antimicrobial activity against multi-drug-resistant strains was screened from 10 kinds of Chinese herbal medicine,and its antimicrobial components were extracted and separated.Finally,the antimicrobial activity and mechanism of the antimicrobial components obtained were studied.The results provided a theoretical basis for the development of new clinical medicines.The main conclusions are as follows:Based on the results of drug sensitivity and drug resistance characteristic,one multi-drug resistant strain with strong biofilm formation and broad-drug resistance spectrum was screened from 81clinically-derived E.coli strains,designated as Ec04 and used as the research objective for subsequent analysis.Ec04 MDR E.coli was used for the test strain,and the antibacterial activity of 10 traditional Chinese medicines including rhubarb was analyzed.The results showed the syringa alcohol extract had obvious antibacterial activity against Ec04 MDR E.coli.The main active ingredient eugenol in the eugenol extract was separated and purified by organic solvent extraction and column chromatography to obtain a solution of eugenol monomer.It was identified by FeCl₃ reaction,TLC and ¹H-NMR.The result indicated the monomer is eugenol.The content and purity of eugenol was 8.23 mg/mL and 97.43%,respectively.The antibacterial activity of eugenol monomer against Ec04 MDR E.coli was analyzed by micro-diluted dilution and agar diffusion method.The MIC and MBC density were 2.5 mg/mL and 5 mg/mL,respectively.Moreover,the results showed that eugenol could prolong the progression of Ec04 from the lag phase to the logarithmic growth phase,increasing the soluble protein content and extracellular nucleic acid content of the strain,and the conductivity in the culture medium and destroying the formation of the biofilm.