In 17th-century Poland, wet bread mixed with spider webs was used to cure wounds. It may sound stupid, but it work, as the bread contained fungal spores, including penicillin and naturally produced antibiotic substances.
Alexander Fleming discovered penicillin, but never tried to make an antibiotic out of it. It was not until a decade later that a man named Howard Florey found Fleming’s little-known paper and realized the mold’s potential. Florey’s work is estimated to have saved up to 200,000,000 lives.
Penicillin was formally discovered when Alexander Fleming did not tidy up some petri dishes filled with bacteria before going on vacation. A penicillin spore then spontaneously landed in a petri dish and caused enough damage to the bacteria for Fleming to notice this when he came back.
It was a lucky chance that we tested penicillin on mice instead of guinea pigs, because penicillin is toxic to guinea pigs and thus penicillin would have been discarded. This possibly would have never made us realize the field of antibiotics.
Centuries before the actual discovery of penicillin, many ancient cultures were using moldy food to treat infection without understanding how it worked.
Penicillin was so scarce and precious before 1944 that it was extracted from the patients’ urine to be re-used.