Resistance to vancomycin is due to the presence of operons that encode enzymes (1) for synthesis of low-affinity precursors, in which the C-terminal D-alanine residue is replaced by D-lactate, thus modifying the vancomyin-binding target; and (2) for elimination of the high-affinity precursors that are normally produced by the host, thus removing the vancomycin-binding target.
