title: Vancomycin resistance reversal in enterococci by flavonoids.
abstract: The development of clinical vancomycin-resistant strains of enterococci (VRE) is a major cause for concern. Here we show that a combination of galangin or 3,7-dihydroxyflavone with vancomycin may be used to sensitize resistant strains of Enterococcus faecalis and Enterococcus faecium to the level of vancomycin-sensitive strains. Minimum inhibitory concentrations (MICs) and viable counts were determined in Iso-sensitest broth using a microtitre method. MICs of vancomycin against 67% of resistant clinical isolates and a type strain of enterococci were lowered from > 250 microg mL(-1) to < 4 microg mL(-1) in the presence of galangin (12.5 microg mL(-1)) or 3,7-dihydroxyflavone (6.25 microg mL(-1)). Viable counts for type culture E. faecalis ATCC 51299 showed the flavonoids alone significantly lowered numbers of colony forming units (CFUs). CFUs were maintained at low levels (< 10(3) CFU mL(-1)) for 24 h by vancomycin/flavone combinations. This combinational action in reversing vancomycin resistance of enterococci highlights novel drug targets and has importance in the design of new therapeutic regimes against resistant pathogens.
authors.affiliation: School of Pharmacy, Faculty of Health and Social Care, The Robert Gordon University, Aberdeen, UK.
authors.forename: L X
authors.initials: LX
authors.lastname: Liu
authors.forename: D G
authors.initials: DG
authors.lastname: Durham
authors.forename: R M
authors.initials: RM
authors.lastname: Richards
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004347:Drug Interactions; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000472:pathogenicity; D016984:Enterococcus faecium / Q000187:drug effects* / Q000472:pathogenicity; D005419:Flavonoids / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009153:Mutagens / Q000494:pharmacology*; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance
chemical_list: D000900:Anti-Bacterial Agents; D005419:Flavonoids; D009153:Mutagens; C037032:galangin; D014640:Vancomycin; C422925:3,7-dihydroxyflavone