ELI5: Explain Like I'm 5

History of penicillin

When people get sick, they sometimes need medicine called antibiotics to help them get better. A long time ago, people didn't have antibiotics so if they got sick, they often couldn't get better and sometimes they even died.

A man named Alexander Fleming was a scientist who liked to study tiny things that you can't see called bacteria. He was trying to find a way to help people who got infected by these bacteria that were making them sick.

One day, Alexander Fleming was leaving his lab to go on vacation and he left some petri dishes, which are like very small flat plates with a lid, with bacteria growing on them on his workbench. When he came back from vacation and looked at the petri dishes, he saw that some mold had grown on one of them. But he noticed that the bacteria around the mold seemed to be dying.

He was very curious about this and he studied it more closely. He discovered that this mold was called penicillin and it could help kill off bacteria and help people get better! This was a really big discovery because before this, people didn't know how to stop infections caused by bacteria.

After studying this mold, other scientists worked hard to make more of it and figure out how to give it to people so it could help fight infections. Now, penicillin is an important medicine that doctors use to help people get better when they have infections caused by bacteria.