Vancomycin-resistant Enterococcus (VRE) infections are especially aggressive and have been associated with mortality rates approaching 60% to 70%. They are now the second-leading cause of nosocomial infections in the U.S., and their prevalence is increasing worldwide. Resistance to vancomycin has the potential to be transferred from bacteria to bacteria. Cross-resistance is mediated by plasmids and transposons, which transfer the genes associated with resistance to other much more aggressive pathogens, such as staphylococci and streptococci.

Three principal types of vancomycin resistance are found in Enterococci; VanA, VanB and VanC. VanA and VanB type are transmissible resistance and account for most significant infections in clinical settings, involving E.faecium and E.faecalis. VanC resistance is a low-level intrinsic resistance found in other species of Enterococcus. Therefore, a simple, fast and reliable tool for the direct detection of VRE strains with transmissible resistance is a precious help in the implementation of the appropriate control measures to prevent the spread of VRE. In the new CHROMagar^TM VRE media, transmissible vancomycine resistant Enterococcus strains are easily distinguishable by the colony colour.