Abstract
Aim: To investigate the action mechanism of 1-benzyl-1,4-diazepane (1-BD) as efflux pump inhibitor (EPI) in Escherichia coli mutants: ΔacrAB or overexpressing AcrAB and AcrEF efflux pumps. Materials & methods: Effect of 1-BD on: antibiotic potentiation, by microdilution method; membrane functionality, by fluorimetric assays; ethidium bromide accumulation, by fluorometric real-time efflux assay; AcrB expression, by quantitative photoactivated localization microscopy. Results: 1-BD decreases the minimal inhibitory concentration of levofloxacin and other antibiotics and increase ethidium bromide accumulation in E. coli overexpressing efflux pumps but not in the ΔacrAB strain. 1-BD increases membranes permeability, without sensibly affecting inner membrane polarity and decreases acrAB transcription. Conclusion: 1-BD acts as an EPI in E. coli with a mixed mechanism, different from that of major reference EPIs.
Keywords:
AcrAB expression; E. coli; EPI; MDR; efflux-pump inhibitor; levofloxacin potentiation; membrane permeability; multidrug resistance.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Anti-Bacterial Agents / pharmacology*
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Azepines / pharmacology*
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Drug Resistance, Multiple, Bacterial
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Escherichia coli / drug effects*
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Escherichia coli / genetics
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Escherichia coli / metabolism*
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Escherichia coli Infections / drug therapy
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Escherichia coli Infections / microbiology
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Escherichia coli Proteins / genetics
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Escherichia coli Proteins / metabolism
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Humans
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Levofloxacin / pharmacology
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Lipoproteins / genetics
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Lipoproteins / metabolism
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Membrane Transport Proteins / genetics
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Membrane Transport Proteins / metabolism
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Microbial Sensitivity Tests
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Multidrug Resistance-Associated Proteins / genetics
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Multidrug Resistance-Associated Proteins / metabolism
Substances
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1,4-diazepane
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AcrA protein, E coli
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AcrB protein, E coli
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Anti-Bacterial Agents
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Azepines
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Escherichia coli Proteins
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Lipoproteins
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Membrane Proteins
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Membrane Transport Proteins
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Multidrug Resistance-Associated Proteins
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acrE protein, E coli
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acrF protein, E coli
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Levofloxacin