I believe penicillin is dead mold cells, that force yoour body to create antibodies, but are also dead so they don't fight back. You build an immunity to it, but it is still POSSIBLE to catch the malady.

Gu, this isn't a discussion of who invented the penicillin, and what penicllin is. This is a thread where people make their own stories of what they would do, based on the facts I wrote down in the first post.