Florey, Sir Howard Walter (1898-1968)
Australian pathologist whose research into lysozyme, an antibacterial enzyme discovered by Alexander Fleming, led him to study penicillin (another of Fleming's discoveries), which he and Ernst Chain isolated and prepared for widespread use. With Fleming, they were awarded the Nobel Prize for Physiology or Medicine 1945.

Florey was born in Adelaide and educated there and at Oxford University, England. He was professor of pathology at Sheffield 1932-35 and at Oxford from 1935.
Florey and his co-worker Chain found that penicillin did not behave like an antiseptic or an enzyme, but blocked the normal process of cell division. Their experiments showed that penicillin could protect against infection but that the concentration of penicillin in the human body and the length of time of treatment were vital factors.
In 1940, during the early part of World War II, a German invasion of Britain seemed imminent; Florey and his colleagues smeared spores of the Penicillium mould on their coat linings so that, if necessary, any one of them could continue their research elsewhere.
In 1943, Florey went to Tunisia and Sicily and used penicillin successfully on war casualties. By 1945, it was established that antibacterial activity could take place using a dilution of 1 part in 50 million and, with the war over, large-scale commercial production of penicillin began.
Florey and his co-workers resumed their researches on other antibiotics. They discovered cephalosporin C, which later became the basis of some derivatives, such as cephalothin, that can be used as an alternative antibiotic to penicillin.