Seven glycopeptide resistance genotypes have been described in enterococci.
Five of these(vanA, vanB, vanD, vanE and vanG) are acquired mechamechanisms and the other two (vanC1 and vanC2/C3) are intrinsic properties.
vanA and vanB are the most common resistance genotypes.
The vanA genes encode proteins that confer high-level resistance to vancomycin and teicoplanin.
The expression of vanA genes is induced by either vancomycin or teicoplanin.