Study On β-lactam Antibiotic Synergist And Its Application In Eliminating E.coli Resistance

The increase of drug resistance of E.coli leads to the unsatisfactory therapeutic effect of antibiotics on colibacillosis.The development speed of antibiotics is far less than that of bacterial resistance.In order to improve the effect of antibiotics on drug-resistant E.coli,the development of antibiotic synergists has been highly concerned.In this study,the effective components that can significantly eliminate the drug resistance of E.coli were screened from 11 main effective components of Hawthorn and coptis chinensis,and the compositions that can eliminate the drug resistance of E.coli were identified.The sensitivity of multidrug-resistant E.coli toβ-lactam antibiotics was verified,which provided a theoretical basis for the development of new synergists.The main findings are as follows:1.Screening of effective components of chinese medicine for eliminating drug resistance of E.coli.After the multi-drug resistant E.coli was treated with the effective components of traditional chinese medicine,the effective components to eliminate the drug resistance of E.coli were screened by agarose gel electrophoresis,q PCR and ELISA.The results showed that the components that significantly eliminated drug-resistant plasmids were Citric acid,Hawthorn acid and Berberine in turn.Citric acid and rutin significantly reduced the transcription levels of Acr A,Acr B and Tolc genes in the efflux system.The components that significantly inhibited ESBLs activity were Oleanolic acid,Citric acid and Berberine.The components that significantly inhibited biofilm formation were Rutin and Kaempferol.This indicates that different Chinese medicinal ingredients have different mechanisms and effects in eliminating E.coli drug resistance.2.Elimination of E.coli resistance combinations screening.Using Citric acid,Rutin and Berberine as raw materials,the composition was screened by chessboard dilution method,orthogonal test and Oxford cup method.The results showed that the FICI of Berberine and Rutin was 0.09,showing a synergistic effect.The FICI of Berberine and Citric acid,Citric acid and Rutin was 1.03,indicating that the combination of Citric acid and Berberine and Rutin had no antagonistic effect.The combination of Citric acid,Rutin and Berberine（2:1:2）had the best effect on eliminating drug resistance,indicating that the combination of Citric acid,Rutin and Berberine had synergistic effect.3.Study on the effect ofβ-lactam antibiotic synergists in vitro.After treating 20strains of E.coli multi-resistant toβ-lactam antibiotics with active ingredient composition,the resistance phenotype and resistance gene of E.coli were detected by double dilution method and PCR method.The results showed that the combination could enhance the sensitivity of E.coli to 6 kinds ofβ-lactam antibiotics such as Amoxicillin and Ceftriaxone,and eliminate bla _CTX-M,bla _TEM,and bla _SHVESBLs resistance genes.The elimination effect of bla _TEMwas the best,and the elimination rate reached 72.0%.This indicating that this composition is universal in eliminating E.coli resistance.In summary,the combination of Citric acid,Rutin,Berberine（2:1:2）and Amoxicillin,Ceftriaxone and other 6 kinds ofβ-lactam antibiotics has synergistic effect,indicating that the composition has the potential to develop into aβ-lactam antibiotics synergist.