Antimicrobial action, target sites

The antimicrobial antibiotics have a selectively toxic action on invading bacteria, by virtue of exploiting differences in cellular characteristics between microorganisms and their human host cells. Major target sites are the bacterial cell wall located outside the cell membrane (animal cells have only a cell membrane). and the bacterial ribosome - the protein-synthesizing organelle within its cell - which is different between bacteria and animal cells. Viruses lack both cell walls and ribosomes and so are resistant to these and other similar antibiotics. A classification of therapeutically used antibiotics can be attempted on the basis of these mechanisms. 

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