How long have antibiotics been invented?

Answer 1

The first observations that penicillium mold killed bacteria was in 1874.

Sir Alexander Fleming identified penicillin as the chemical produced by penicillium mold that killed bacteria in 1928. He was able to separate small quantities of penicillin.

Ernst Chain, Howard Florey and Edward Abraham succeeded in purifying the first penicillin, penicillin G, in 1942 for the Allied military, but it did not become available outside the Allied military before 1945.

However the rapid development of antibiotic resistance due to antibiotic misuse has resulted in penicillin and many other antibiotics now being ineffective on most bacteria. There is only one remaining antibiotic (vancomycin) to which no bacteria have developed any resistance!