Antimicrobial Agents and Chemotherapy 2007-12-01

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

Index: Antimicrob. Agents Chemother. 51 , 4480-3, (2007)

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Abstract

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 microM (1/4x 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.