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In the 19th century many people got sick and died after they
had operations because of infection. But doctors didn't know about
it. That is why they didn't wear special clothes during operations
didn't always wash their hands or clean their instruments.
A British doctor, Joseph Lister, knew that infection was caused
by germs.In his hospital doctors started to wear special white
clothes.They regularly washed their hands and cleaned their
instruments before and after operations. It saved many sick
people in the hospital.
In 1928 a British scientist Alexander Fleming worked in his
laboratory at St Mary's Medical School. With the help of his
microscope he studied some green mould and saw that it
killed the germs, which were near it.
It was a very important discovery which Fleming called peni-
cillin, it was the first medicine against infection. But it was
too expencive to make. In 1941 Henry Florey and Ernst Chain from Oxford found a cheaper way to make the medicine and it
saved millions of people. In 1945 the three men got a Nobel
Prize for their work.