AcrAB-TolC Inhibition by Peptide-Conjugated Phosphorodiamidate Morpholino Oligomers Restores Antibiotic Activity in Vitro and in Vivo

Carolyn R. Sturge, Christina F. Felder-Scott, Reed Pifer, Christine Pybus, Raksha Jain, Bruce L. Geller, David E Greenberg

Research output: Contribution to journalArticle

1 Scopus citations


Overexpression of bacterial efflux pumps is a driver of increasing antibiotic resistance in Gram-negative pathogens. The AcrAB-TolC efflux pump has been implicated in resistance to a number of important antibiotic classes including fluoroquinolones, macrolides, and β-lactams. Antisense technology, such as peptide-conjugated phosphorodiamidate morpholino oligomers (PPMOs), can be utilized to inhibit expression of efflux pumps and restore susceptibility to antibiotics. Targeting of the AcrAB-TolC components with PPMOs revealed a sequence for acrA, which was the most effective at reducing antibiotic efflux. This acrA-PPMO enhances the antimicrobial effects of the levofloxacin and azithromycin in a panel of clinical Enterobacteriaceae strains. Additionally, acrA-PPMO enhanced azithromycin in vivo in a K. pneumoniae septicemia model. PPMOs targeting the homologous resistance-nodulation-division (RND)-efflux system in P. aeruginosa, MexAB-OprM, also enhanced potency to several classes of antibiotics in a panel of strains and in a cell culture infection model. These data suggest that PPMOs can be used as an adjuvant in antibiotic therapy to increase the efficacy or extend the spectrum of useful antibiotics against a variety of Gram-negative infections.

Original languageEnglish (US)
JournalACS Infectious Diseases
Publication statusPublished - Jan 1 2019



  • antisense
  • bacterial efflux pumps
  • Escherichia coli
  • Klebsiella pneumoniae
  • peptide-conjugated phosphorodiamidate morpholino oligomers (PPMOs)
  • Pseudomonas aeruginosa

ASJC Scopus subject areas

  • Infectious Diseases

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