Penicillin protects mice against infection
The story of Sir Alexander Fleming's discovery of penicillin is well known. In 1929 he discovered a mould growing on a glass dish in his laboratory which appeared to kill the bacteria he was cultivating. In his follow-up studies, the crude penicillin broth that he had extracted from the mould was non-toxic to rabbits and mice.
These results led Fleming to believe that penicillin would only be useful as an antiseptic for surface infections rather than as a powerful antibiotic for general infections. After this, little came of his discovery, although a few patients with eye infections were successfully treated by the application of impure extracts of penicillin broth in the 1930s.
The enormous death toll from septic infections led to a great interest in developing antibiotics at the beginning of the 1940s. One of the substances tested by researchers was Fleming's crude penicillin broth.
Howard Florey and Ernst Chain, searching for potential antibiotics at Oxford University in 1940, used the mouse protection test. This animal test was first described in 1911 and was in routine use from 1927. In the test, Florey and Chain injected eight mice with a lethal suspension of bacteria, and four of these were also given penicillin. The four mice which received penicillin lived and all the rest died, giving definite proof that penicillin worked as an antibiotic against serious bacterial infections. It was this test which set Florey, Chain, Heatley and others on the long road to purifying and mass producing penicillin.
In 1945, Alexander Fleming, Ernst Chain and Howard Florey received the Nobel Prize for the discovery and development of penicillin.
- Fleming A (1929) Brit J Exper Path 10, 226
- Florey H (1953) Conquest 41, 4