Vancomycin resistance reversal in enterococci by flavonoids.
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.
Liu
L X
LX
School of Pharmacy, Faculty of Health and Social Care, The Robert Gordon University, Aberdeen, UK.
Durham
D G
DG
Richards
R M
RM
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
D000900:Anti-Bacterial Agents; D005419:Flavonoids; D009153:Mutagens; C037032:galangin; D014640:Vancomycin; C422925:3,7-dihydroxyflavone