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Identification of efflux pump-mediated multidrug-resistant bacteria by the ethidium bromide-agar cartwheel method.

BACKGROUND/AIM:
Bacterial multidrug resistance may be mediated by the overexpression of efflux pumps. Conventional evaluation of efflux activity using efflux pump substrates, such as ethidium bromide, requires specialised instrumentation. The agar-based method, previously reported, has been modified to evaluate as many as twelve bacterial strains and has been termed the ethidium bromide-agar cartwheel method.
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Genetic response of Salmonella enterica serotype Enteritidis to thioridazine rendering the organism resistant to the agent.

Thioridazine (TZ)-induced accumulation of the universal efflux pump substrate ethidium bromide and its subsequent efflux by Salmonella strains with various degrees of overexpressed efflux pumps takes place automatically at pH 7.4, is independent of a metabolic source, is not affected by a proton ionophore and is precluded by palmitic acid.
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Exploring the contribution of efflux on the resistance to fluoroquinolones in clinical isolates of Staphylococcus aureus.

BACKGROUND:
Antimicrobial resistance mediated by efflux systems is still poorly characterized in Staphylococcus aureus, despite the description of several efflux pumps (EPs) for this bacterium. In this work we used several methodologies to characterize the efflux activity of 52 S. aureus isolates resistant to ciprofloxacin collected in a hospital in Lisbon, Portugal, in order to understand the role played by these systems in the resistance to fluoroquinolones.
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Identification of the plasmid-encoded qacA efflux pump gene in meticillin-resistant Staphylococcus aureus (MRSA) strain HPV107, a representative of the MRSA Iberian clone

Meticillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial bacterium for which prevention and control measures consist mainly of the application of biocides with antiseptic and disinfectant activity.
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Enhancing activity of antibiotics against Staphylococcus aureus: Zanthoxylum capense constituents and derivatives

Six compounds (1-6), isolated from the methanol extract of the roots of the African medicinal plant Zanthoxylum capense Thunb. (Rutaceae), and seven ester derivatives (7-13) were evaluated for their antibacterial activities and modulatory effects on the MIC of antibiotics (erythromycin, oxacillin, and tetracycline) and ethidium bromide (EtBr) against a Staphylococcus aureus reference strain (ATCC 6538). Using the same model, compounds 1-13 were also assessed for their potential as efflux pump inhibitors by a fluorometric assay that measures the accumulation of the broad range efflux pump substrate EtBr. Compounds 8 and 11 were further evaluated for their antibacterial, modulatory and EtBr accumulation effects against four additional S. aureus strains, which included two clinical methicillin-resistant S. aureus (MRSA) strains.
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