Ernest Duchesne discovered penicillin 32 years before Alexander Fleming, but he was ignored because he was only 23!
Duchesne was a French physician who noted that certain moulds killed bacteria. This was 32 years before Alexander Fleming found the antibiotic properties in penicillin. Duchesne enrolled at the Military Health Service Schools of Lyons in 1894 and documented his findings in his thesis paper on the antagonisms between moulds and microbes.
He made his discovery by observing how Arab stable boys at the army hospital kept the saddles in a dark and damp room to encourage mould growth. They told Duchesne that the mould helped heal the saddle sores on the horses. Duchesne took the information and experimented on guinea pigs.
Due to his age, though, his research went unrecognized and he was unable to continue research himself, because of his army service. In 1949, five years after Fleming won the Nobel Peace Prize, Duchesne was posthumously honored as the original discoverer of penicillin.