re: OT Doctors- Why do we become immune to antibiotics?

ELY5 because apparently you are.

Antibiotics kill bacteria. This was discovered in 1928 (and you're just now finding out about it! how exiting!).

Their success depends on the type of antibiotic you use. But in general they break down the bacterium's cell walls.

We don't develop an immunity to antibiotics, the bacteria do. This is why the immunity is so dangerous - it means that you are now at risk of dying just from a simple cut to your hand.

The bacteria develop immunity because... wait for it... evolution. The bacteria that aren't totally killed by the antibiotics live on and pass their traits to their offspring which are now just a little bit stronger against the medicines. Only, bacteria go through generations very very quickly, so while it make take you forever to evolve, it only takes them a few days.

Now, see what a 10th grade education can do for you? Stay in school, one day you'll know this stuff too.