A selective membrane-targeting repurposed antibiotic with activity against persistent methicillin-resistant Staphylococcus aureus

Proc Natl Acad Sci U S A. 2019 Aug 13;116(33):16529-16534. doi: 10.1073/pnas.1904700116. Epub 2019 Jul 29.


Treatment of Staphylococcus aureus infections is complicated by the development of antibiotic tolerance, a consequence of the ability of S. aureus to enter into a nongrowing, dormant state in which the organisms are referred to as persisters. We report that the clinically approved anthelmintic agent bithionol kills methicillin-resistant S. aureus (MRSA) persister cells, which correlates with its ability to disrupt the integrity of Gram-positive bacterial membranes. Critically, bithionol exhibits significant selectivity for bacterial compared with mammalian cell membranes. All-atom molecular dynamics (MD) simulations demonstrate that the selectivity of bithionol for bacterial membranes correlates with its ability to penetrate and embed in bacterial-mimic lipid bilayers, but not in cholesterol-rich mammalian-mimic lipid bilayers. In addition to causing rapid membrane permeabilization, the insertion of bithionol increases membrane fluidity. By using bithionol and nTZDpa (another membrane-active antimicrobial agent), as well as analogs of these compounds, we show that the activity of membrane-active compounds against MRSA persisters positively correlates with their ability to increase membrane fluidity, thereby establishing an accurate biophysical indicator for estimating antipersister potency. Finally, we demonstrate that, in combination with gentamicin, bithionol effectively reduces bacterial burdens in a mouse model of chronic deep-seated MRSA infection. This work highlights the potential repurposing of bithionol as an antipersister therapeutic agent.

Keywords: MRSA; bacterial persister; drug repurposing; membrane selectivity; membrane-active antimicrobials.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Bithionol / pharmacology
  • Cell Membrane / drug effects*
  • Cell Membrane Permeability / drug effects
  • Cholesterol / chemistry
  • Disease Models, Animal
  • Drug Repositioning*
  • Drug Synergism
  • Gentamicins / pharmacology
  • Lipid Bilayers / chemistry
  • Membrane Fluidity / drug effects
  • Methicillin-Resistant Staphylococcus aureus / drug effects*
  • Methicillin-Resistant Staphylococcus aureus / ultrastructure
  • Molecular Dynamics Simulation
  • Phosphatidylcholines / chemistry
  • Structure-Activity Relationship
  • Unilamellar Liposomes


  • Anti-Bacterial Agents
  • Gentamicins
  • Lipid Bilayers
  • Phosphatidylcholines
  • Unilamellar Liposomes
  • Cholesterol
  • Bithionol
  • 1-palmitoyl-2-oleoylphosphatidylcholine