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Although antibiotics may get a criticism for their prevalence and overuse, life before them was fraught with untamable infection and few defensive tools. Penicillin was the first antibiotic, a discovery that happened in 1929 when a young bacteriologist, Sir Alexander Fleming, was making some alterations in his lab. After having been on vacation, he returned to work to find that a petri dish of Staphylococcus bacteria had been left uncovered; and he noticed that mold on the culture had killed many of the bacteria. He identified the mold as penicillium notatum, and upon further research found that it could kill other bacteria and could be given to small animals without ill effect. A decade later, Howard Florey and Ernst Chain picked up where Fleming left off and isolated the bacteria-killing substance found in the mold – penicillin. The three won the Nobel Prize in medicine in 1945 for the discovery of penicillin and its curative effect in various infectious diseases. A laboratory worker measures purified penicillin into bottles. In this process, the substance is freeze-dried and the ice evaporated off under vacuum. The powder left behind is penicillin.