Why do some antimicrobial agents affect bacteria, but not humans? Does anyone know?

antimicrobial agents apply to substances that control the growth of bacteria, fungi, or viruses. since these subtances include a lot, their mode of action is also very diverse. for example in an antibiotic, the binding site in prokaryote(bacterium) is different than that in eukaryote, such as a human. antibiotics could bind to a component of a ribosome which could affect the protein synthesis.

thanks.... so it's sorta like how enzymes and activation enzymes work.. in a way.. like how it should have certain shapes and binding sites so that they'll match up...

antimicrobial agents apply to substances that control the growth of bacteria, fungi, or viruses.

 

Viruses of course do not grow. Agents that deactivate viruses are aggressive substances as hydrogen peroxide, bleach etc. that would of course also harm cells.

 

Also for the record, fungi are eukaryotes, most substances harming them is also potentially toxic for other eukaryotes, as humans. That being said, fungi cells do possess certain features distinguishing them from mammalian, as the presence of ergosterines in the cell membrane. These are then potential targets of antifungal substances. However, due to the large similarities between mammalian and fungal cells there are overall less potential targets.

 

Finally, for bacteria there are a number specific agents like antibiotics.

Their specificity for bacteria is of course, as mentioned, due to the large cellular differences between prokaryotic and eukaryotic cells.

Examples are prokaryotic ribsomes (a common target for antiobiotics), which are structurally very different to eukaryoticy ones, or bacterial cell walls (eukaryotes either have none or e.g. in plants one with a very different chemical composition), bacterial LPS and so on.

 

In essence these compounds simply target elements of the target cell that are not present or are structurally different in mammalian cells.

in short, that means such antibacterial agents act on specific sites on the target which is not found in human cells, this is achievable due to the uniqueness of each species or even individual.