Correlation And Mechanism Of Combined Toxicity And Resistance Of Mixed Antibiotics Based On Antimicrobial Peptide

The use and abuse of antibiotics has led to the serious problem of bacterial resistance.The main reason for antibiotic resistance in bacteria is to acquire antibiotic resistance genes(ARGs).Controlling the generation and transmission of ARGs can reduce the problem of bacterial resistance.Current studies have shown that antimicrobial peptide(AMPs)show high antibacterial effect and low ecological and environmental risk,with a low tendency of drug resistance.Based on two measures to reduce drug resistance,can AMPs and aminoglycoside antibiotics be used together to reduce drug resistance while ensuring drug efficacy? AMPs can be divided into membrane-targeting peptide(M-AMPs)and non-membrane-targeted peptide(NM-AMPs)due to their different mechanisms of action.How can the combination of these two AMPs reduce drug resistance and improve antibacterial effect? Quorum Sensing inhibitors(QSIs)are considered to be one of the new antibiotics that are not easy to develop resistance to bacteria,so can the combination of AMPs and QSIs improve antibacterial effect and reduce the generation and transmission of ARGs?Based on the above key problems,Escherichia coli(E.coli)was used as a model organism in this study,and 7 AMPs species(5 M-AMPs,2 NM-AMPS),the traditional antibiotic Kanamycin sulfate(KAN)was selected as the standard,and the new antibiotic QSIs(2-P,HDMF,25HF)was selected as the research object.The combined toxicity,mutation and conjugation transfer effects of AMPs-KAN,AMPs-AMPS and AMPs-QSIS on E.coli were determined.The main results are as follows:(1)Combined toxicity and resistance of AMPs(M-AMPS,NM-AMPS)and KAN to E.coli:The results showed that M-AMPs&KAN and NM-AMPs&KAN mixtures inhibited bacterial growth,and the dose-response curve presented an "S" shape,which promoted E.coli mutation and plasmid conjugated transfer.Based on IA model discrimination,the combined toxicity mode of M-AMPs&KAN and NM-AMPs&KAN mixture was antagonistic,while the combined resistance mode was antagonistic → additive →synergistic.Mechanism analysis showed that combined toxicity and resistance were closely related to ROS produced by the interaction of target proteins.(2)The combined toxicity and resistance of AMPs(M-AMPS and NM-AMPS)to E.coli:The results showed that M-AMPS&M-AMPs and NM-AMPS&M-AMPs inhibited E.coli growth,and the dose-response curve was "S" shape,which promoted E.coli mutation and plasmid conjugated transfer.Based on IA model discrimination method,the combined toxicity mode of M-AMPS&M-AMPs and NM-AMPS&M-AMPs was antagonistic,while the combined resistance mode was antagonistic → additive →synergistic.Mechanism analysis showed that combined toxicity and resistance were closely related to ROS production.(3)The combined toxicity and resistance of AMPs(M-AMPS,NM-AMPS)and QSIs to E.coli:The results showed that M-AMPs&QSIs and NM-AMPs&QSIs mixtures promoted e.coli growth,mutation and plasmid conjugation transfer.Based on the IA model discrimination method,the combined toxicity mode of M-AMPs&QSIs was antagonistic,while the mode of combined resistance was synergistic → additive → antagonistic.The mode of combined toxicity of NM-AMPs&QSIs was antagonistic,while the mode of combined resistance was antagonistic → additive → synergistic.The mechanism analysis showed that the change of combined toxicity and combined resistance pattern with concentration was closely related to ROS.This study can provide some reference value for the combined use of AMPs with itself,traditional antibiotics and new antibiotics QSIs,and provide scientific basis and theoretical guidance for reducing bacterial resistance.