The purpose of antibiotics (antibacterials)
Counter-intuitively, the aim of antibiotics is not to rid the body or target the organ concerned, of all bacteria. It may be possible that the human body consists of around one trillion human cells, and 10 trillion bacterial cells that keep us alive. They keep out environmental insults, helping us to stay healthy. They digest food, make vitamins and educate the immune system to keep bad microbes out.
Carried around with us are bacteria that could potentially harm us, but normally they are kept in check and passive. However, in certain situations they sense an opportunity to become aggressive, new ones arrive, communicate with each other, multiply, move to new vulnerable sites and exploit the body for their own purposes. They can then possibly destroy tissue, release toxins and/or threaten to move to new tissue. It is then that we need to supplement our defences with antibiotics.