biostudies-literatureUnknown5(1)Vergalli JSufficient concentration of antibiotics close to their target is key for antimicrobial action. Among the tools exploited by bacteria to reduce the internal concentration of antibiotics, multidrug efflux pumps stand out for their ability to capture and expel many unrelated compounds out of the cell. Determining the specificities and efflux efficiency of these pumps towards their substrates would provide quantitative insights into the development of antibacterial strategies. In this light, we developed a competition efflux assay on whole cells, that allows measuring the efficacy of extrusion of clinically used quinolones in populations and individual bacteria. Experiments reveal the efficient competitive action of some quinolones that restore an active concentration of other fluoroquinolonesCommunications biology1062https://www.ebi.ac.uk/biostudies/studies/S-EPMC9537517biostudies-literatureA framework for dissecting affinities of multidrug efflux transporter AcrB to fluoroquinolones.PMC9537517Chauvet HRefregiers MMalloci GPajovic JRuggerone PVergalli JOliva FPages JMVargiu AVfalseA framework for dissecting affinities of multidrug efflux transporter AcrB to fluoroquinolones.Sufficient concentration of antibiotics close to their target is key for antimicrobial action. Among the tools exploited by bacteria to reduce the internal concentration of antibiotics, multidrug efflux pumps stand out for their ability to capture and expel many unrelated compounds out of the cell. Determining the specificities and efflux efficiency of these pumps towards their substrates would provide quantitative insights into the development of antibacterial strategies. In this light, we developed a competition efflux assay on whole cells, that allows measuring the efficacy of extrusion of clinically used quinolones in populations and individual bacteria. Experiments reveal the efficient competitive action of some quinolones that restore an active concentration of other fluoroquinolones2022-01-01T00:00:00Z2022 Oct2025-04-25T17:37:09.039Z2025-04-06T05:06:15.427ZS-EPMC95375173620303010.1038/s42003-022-04024-1