Different antibiotics work different ways, but they target things that bacterial cells have, like a cell wall, but a human cell does not have, so our cells remain unharmed. They are not very specific tho, so they would kill the "Good" bacteria that we have in our body. read more
Human cells do not make or need peptidoglycan. Penicillin, one of the first antibiotics to be used widely, prevents the final cross-linking step, or transpeptidation, in assembly of this macromolecule. The result is a very fragile cell wall that bursts, killing the bacterium. read more
This allows human cells to have negligible responses to antibiotics but if the bacteria are resistant to most common antibiotics, more serious antibiotics may have to be used and some of these drugs are dangerous to the kidneys and can only given to patient in the hospital to monitor kidny function. read more