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In the late 1800’s there were many accounts by both physicians as well as doctors about the antibacterial properties of different kinds of mold. This included the mold penicillium but the accounts were unable to discern what the process was that caused the effect. The effects of penicillium mold would finally be identified in 1928 by a Scottish scientist named Alexander Fleming. This was to occur in work that would seem to have been independent of these earlier observations. The all important date of his discovery, penicillin, was the morning of Friday 28 September 1928.

The story goes that the discovery was by total accident. It happened in his laboratory in the basement at St Mary’s Hospital in London. Fleming noticed that a Petri dish which was containing Staphylococcus had been mistakenly left open and was contaminated by blue-green mold. This was due to an open window. A visible growth formed. There was a halo of inhibited bacterial growth all around the mold. After studying the event he concluded that the mold released a substance that repressed growth and caused lysing of the bacteria. After making this discovery he then grew a pure culture only to discover it was the Penicillium mold, known as Penicillium chrysogenum.

Fleming was the one to come up with the term “penicillin” to describe the filtrate of a broth culture of the Penicillium mold. Fleming then asked C.J. La Touche to help identify the mold. It was incorrectly identified it as Penicillium rubrum and was later corrected by Charles Thom. He expressed initial optimism in that penicillin would be a useful disinfectant. This is because of its high potency and minimal toxicity in comparison to antiseptics that were being used then. Its laboratory value was noted in the isolation of Bacillus influenzae (now called Haemophilus influenzae).

Fleming was a very poor communicator and orator, this meant that his findings were not given very much attention initially. He wasn’t even able to convince a true chemist to help him extract and stabilize the antibacterial compound that he had found in his broth filtrate. Despite the lack of chemist, he always remained interested in the potential use of penicillin. He presented a paper entitled “A Medium for the Isolation of Pfeiffer’s Bacillus” to the Medical Research Club of London. This was met with very little interest and less enthusiasm by peers. Had Fleming been able to get some other scientists interested in his work then penicillin for medicinal use would have likely been developed years earlier.

He conducted several experiments on the antibiotic substance. The most important results would prove that it was nontoxic to humans. He discovered this by first performing toxicity tests in animals, then he moved on to humans.