The phenolic diterpene totarol inhibits multidrug efflux pump activity in Staphylococcus aureus

Eileen C. J. Smith, Glenn W. Kaatz, Susan M. Seo, Neale Wareham, Elizabeth M. Williamson, Simon Gibbons

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The phenolic diterpene totarol had good antimicrobial activity against effluxing strains of Staphylococcus aureus. Subinhibitory concentrations reduced the MICs of selected antibiotics, suggesting that it may also be an efflux pump inhibitor (EPI). A totarol-resistant mutant that overexpressed norA was created to separate antimicrobial from efflux inhibitory activity. Totarol reduced ethidium efflux from this strain by 50% at 15 μM (1/4× MIC), and combination studies revealed marked reductions in ethidium MICs. These data suggest that totarol is a NorA EPI as well as an antistaphylococcal antimicrobial agent.
Original languageEnglish
Pages (from-to)4480-4483
Number of pages4
JournalAntimicrobial Agents and Chemotherapy
Issue number12
Publication statusPublished - 1 Dec 2007

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