10 of History's Happiest Accidents

Dr. Alexander Fleming, discoverer of penicillin, at work in his laboratory in 1943. Daily Herald Archive/SSPL/Getty Images

Before penicillin — the world's first mass-produced antibiotic drug — millions of people died each year from infected wounds and contagious bacterial diseases like scarlet fever. In World War II, bottles of penicillin saved countless lives in battlefield hospitals. Today, we still rely heavily on antibiotics to treat everything from common ear infections to potentially deadly bacterial outbreaks. Yes, mankind owes a tremendous debt to Dr. Alexander Fleming and his marvelous mistake.

Mistake? Absolutely. Scottish-born Dr. Fleming was in his lab in 1928 researching the flu virus when he noticed that one of his bacteria cultures was infected with a fungus. Most scientists would have tossed the spoiled petri dish in the trash, but not Fleming. Six years earlier, he had discovered the mild antibiotic properties of human tears when one of his own accidentally dripped into a bacterial sample [source: Krok]. Even mistakes, Fleming learned, had scientific value.

Upon closer inspection, Fleming noticed a clear ring around the fungus, indicating that it was toxic to the staphylococcus bacteria in the dish. Fleming carefully isolated the mold, which was of the genus Penicillium, and named his new wonder drug penicillin. The rest, as they say, is fungus history. Fleming was awarded the Nobel Prize in physiology or medicine in 1945 [source: Nobelprize.org].