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Improved Enzyme Protection Assay to Study Staphylococcus aureus Internalization and Intracellular Efficacy of Antimicrobial Compounds
Published on: September 8, 2021
Catechin gallates inhibit multidrug resistance (MDR) in Staphylococcus aureus
Simon Gibbons1, Elisabeth Moser, Glenn W Kaatz
1Centre for Pharmacognosy and Phytotherapy, The School of Pharmacy, University of London, London, UK. simon.gibbons@ulsop.ac.uk
Abstract:
Epicatechin gallate (1) and epigallocatechin gallate (2) were evaluated for their antibacterial and efflux inhibitory activity against a wild-type and three multidrug-resistant (MDR) strains of Staphylococcus aureus. Compound 2 was more active than 1 based on minimum inhibitory concentrations (MICs; 32-64 versus 64->512 microg/mL, respectively). When incorporated into the growth medium at 20 microg/mL, both compounds exhibited a four-fold potentiation of the activity of norfloxacin against a norfloxacin-resistant strain of S. aureus overexpressing the NorA multidrug efflux pump. Against this strain 1 was moderately more potent than 2 as an inhibitor of ethidium efflux, but at < or = 20 microM both compounds paradoxically stimulated efflux. This phenomenon has not been encountered previously in the analysis of inhibitors of multidrug efflux.
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