Penicillin was discovered in 1927 by Alexander Fleming a microbiologist working at St. Mary's Hospital in London.

Fleming was conducting experiments in search of new antibacterial agents, particularly one that would be effective against wound infections. In the course of these experiments, he observed a plate culture of staphylococcus aureus that had been contaminated by a mold. The area around the edge of the mold colony was clear - no bacterial colonies. Apparently, the staphylococcus cells near the mold growth were inhibited or killed by the mold. Further studies of this phenomenon revealed that it was a mold of the genus penicillium that produced a substance which was very potent against staphylococci and hence very attractive as a potential chemotherapeutic agent. Fleming named the substance penicillin.



Penicillin was effective against bacteria in laboratory cultures, but was it effective in the human body? This question needed to be answered. Unfortunately, the amount of penicillin produced in the mold cultures were extremely small. In addition, serious problems were encountered in attempts to isolate and purify penicillin.

The first clinical trial with a crude penicillin preparation was conducted on February 12, 1941. The patient, an oxford policeman, was dying from a staphylococcus infection. The administration of penicillin resulted in an initial dramatic improvement, but five days later, when the supply of penicillin was exhausted, the staphylococci reemerged, the infection spread, and the patient died. This was a tragic end to a trial that did not succeed only because there was not enough penicillin available to treat the patient. The major problem continued to be the 

Britain, at this point, was engaged in a grim war. There was little likelihood that a major share of her national resources could be diverted to an intensive program for development of penicillin. 

Fortunately, the British reports of penicillin attracted the attention of Americans. Asa a result, the Rockefeller Foundation invited Harold W. Florey, a professor of the development of penicillin as a chemotherapeutic agent, and N. G. Heatley, his colleague, to the United States to explore means of large-scale production of penicillin. They arrived in the United States on 2nd July 1941. Meetings were arranged with members of the National Research Council, Charles Thom, a world class mycologist with the US Department of Agriculture and others. Work on penicillin production began immediately at the US Department of Agriculture's Northern Regional Research Laboratory of Peoria, which had a record of achievements in microbial fermentations.

The US office of Scientific Research and Development, aware of the potential of penicillin for treatment of causalities of war, gave this project top priority. Major Pharmaceutical companies and Universities were called in to cooperate in the research and development of penicillin. The results proved dramatic. Fleming's original mold and culture produced 2 units/ml; within a matter of months improvement in technology increased the yield to 900units/ml; today the yield is approximately 50,000units/ml.

In the autumn of 1941, there was little penicillin available in the United States for treatment of patients. One year later, as the result of the collaborative efforts of governments, universities, and industry appreciable quantities were available.