The vanA operon is
effective against all glycopeptides that can initiate induction
including teicoplanin. There are several similar
operons in VRE; the second in importance is the vanB
operon in Tn1547, which confers lower resistance to
vancomycin and none to teicoplanin because this glycopeptide
does not act as an inducer [5]. The vanC and vanE
operons employ serine instead of lactate as the glycopeptide-insusceptible
terminal moiety in the pentapeptide in
peptidoglycan synthesis [4,6].
Variations in the vanA operon that are dependent on the
area that the host pathogen has been isolated have been
identified; for instance, the nucleotide sequence of operons
from strains isolated in the United States differs from
those in the UK [7]. However, this operon can also vary
within a small geographical area and different insertions