Vancomycin belongs to a class of antibiotics called glycopeptides. Drugs in this class are composed of a cyclic peptide bound by two sugar molecules (glycogen), hence the name glycopeptides!
MOA: binds to D-alanyl-D-alanine on the outer surface of cell membranes preventing cross-linking. This interferes with cell wall synthesis and results in bacterial cell death.
Another way to think of it: cell walls are like LEGO pieces linking together. The more that are linked, the stronger the structure is. Vancomycin prevents this cross-linking leading to an unstable structure.
Vancomycin = think mainly gram-positive coverage including MRSA! (gram-negatives do NOT have a thick cell wall and lack the D-ala-D-ala sequence, making vancomycin useless against them)
NOTE: Recently, the term “red man syndrome (RMS)” has been replaced and is now recognized as “vancomycin flushing syndrome” or “vancomycin infusion reaction”.