Beta-lactam antibiotics inhibit bacterial cell wall synthesis. Fluid accumulates in the naked protoplast , as the cell now devoid of its wall is called, and it bursts resulting in death of the organism. Bacterial peptidoglycan biosynthesis . Peptidoglycan synthase, 3. Dale, Pharmacology, Churchill Livingstone, New York, 1987.
Bacteria have a cytoplasmic membrane much like that of eukaryotes.
Surrounding this membrane is a periplasmic space which is in turn enclosed by a peptidoglycan layer and finally the outer membrane. The complexity of the cell wall of gram negative organisms is quite different from that of gram positive organisms. The composition of the cell wall also varies with species, but a complete discussion of cell wall composition is beyond the scope of this lecture. The mechanism of action for beta-lactams described below represents the simplest explanation. D-alanine is not found in vertebrate tissues thus making it a substrate that is unique to bacteria.