Alternative <i>vanHAX</i> promoters and increased <i>vanA</i>-plasmid copy number resurrect silenced glycopeptide resistance in <i>Enterococcus faecium</i>

Abstract

Our data support a mechanism by which vancomycin-susceptible VVE strains may revert to a resistant phenotype through the use of an alternative, constitutive, vanR-activator-independent promoter and a vanA-plasmid copy number increase.