[9][10] To become vancomycin-resistant, vancomycin-sensitive enterococci typically obtain new DNA in the form of plasmids or transposons which encode genes that confer vancomycin resistance.

For inoculating peri-rectal/anal swabs or stool specimens directly, one method uses bile esculin azide agar plates containing 6 μg/ml of vancomycin.

Black colonies should be identified as an enterococcus to species level and further confirmed as vancomycin resistant by an MIC method before reporting as VRE.

[21] Another antibiotic often used as off-label salvage therapy in systemic VRE infections is oritavancin, a semisynthetic glycopeptide that has demonstrated synergic activity with fosfomycin.

[23][24] In the United States, vancomycin-resistant E. faecium was associated with 4% of healthcare-associated infections reported to the Centers for Disease Control and Prevention National Healthcare Safety Network from January 2006 to October 2007.

Treatment failures in enterococcal infections result from inadequate information regarding glycopeptide resistance of endemic enterococci due to factors such as the presence of VanA and VanB.