Combined Induction Effect Of Traditional Antibiotics And Quorum Sensing Inhibitors On Drug Resistance Of Escherichia Coli

Since the discovery of traditional antibiotics,they have been widely used to treat bacterial infections due to their good antibacterial effects.With the gradual abuse of antibiotics,bacteria have produced antibiotic resistance genes(ARGs)through selfmutation,and can pass Horizontal transfer spreads rapidly and poses a threat to human survival.In order to solve the problem of bacterial resistance caused by ARGs,new antibiotics have been continuously developed and used.Quorum Sensing Inhibitors(QSIs),as a new class of antibiotics,have been used in aquaculture,sewage treatment,and crop disease control,it is very likely to coexist with traditional antibiotics in the environment.Therefore,it is necessary to explore the joint effects of traditional antibiotics and QSIs on bacteria,which will help environmental protection departments to more comprehensively understand the joint exposure risks of traditional and new pollutants,so as to conduct ecological risk assessment of mixed pollutants more effectively.In this paper,toxicity experiments were used to characterize the effect on bacterial growth,bacterial mutations were used to characterize the emergence of bacterial drug resistance,RP4 plasmid conjugation transfer was used to characterize the spread of bacterial drug resistance,aminoglycoside antibiotics(AGs),quinolone antibiotics(QNs)and β-lactam antibiotics(BLAs)are the representatives of traditional antibiotics,and QSIs are the representatives of new antibiotics.Through toxicity experiments,mutation experiments and conjugation transfer experiments,the relationship between traditional antibiotics and The effects of QSIs single and combined effects on the growth of Escherichia coli(E.coli)and the generation and spread of resistance genes,the research results are as follows:1)The single conjugation transfer effects of three types of traditional antibiotics(AGs,QNs,BLAs)and QSIs on E.coli all showed a hormesis effect of "promoting at low concentrations and inhibiting at high concentrations",with the maximum promoting rate ranging from 11.33 % to 98.81 %.2)The single toxic effect and mutation effect of the three QNs on E.coli all showed the hormesis effect of "promoting at low concentration and inhibiting at high concentration".The maximum promotion rate of the three QNs to the growth of E.coli was 17.98%-22.42%.3)The joint conjugation and transfer effects of three types of traditional antibiotics(AGs,QNs,BLAs)and QSIs on E.coli all showed hormesis effect.In addition,the joint conjugation and transfer effects of AGs-QSIs,QNs-QSIs,and BLAs-QSIs mixtures on E.coli showed consistent concentration-dependent characteristics with the increase of mixture concentration,that is,synergistic effect at low concentrations,and increased with the mixture concentration.transformed into antagonism.4)Both the joint toxicity and joint mutation effects of QNs and QSIs on E.coli showed hormesis effects,and at low concentrations,they both promoted the joint toxicity and mutation effects.In addition,the combined toxicity mode of traditional antibiotics and QSIs mixture at low concentrations was antagonistic,and the combined mutation mode was antagonistic;at high concentrations,the combined toxic mode of action was synergistic,and the combined mutation mode was antagonistic.5)According to the toxicity,conjugation transfer and mutation mechanism of a single antibiotic,this paper found that the joint conjugation transfer effect of three types of traditional antibiotics(AGs,QNs,BLAs)and QSIs mixed exposure to E.coli was closely related to the joint toxicity and mutation effect.The research in this paper provides data support and theoretical reference for the ecological risk assessment of the combined exposure of traditional antibiotics and new antibiotics in the environment.