For: Penicillin (band)

The term "penicillin" can also refer to the mixture of substances that are naturally produced.

The term Penam is used to describe the core skeleton of a member of a penicillin antibiotic. This skeleton has the molecular formula R-C₉H₁₁N₂O₄S, where R is a variable side chain.

History

Discovery

The discovery of penicillin is attributed to Scottish scientist and nobel laureate Alexander Fleming in 1928. He showed that if Penicillium notatum was grown in the appropriate substrate, it would exude a substance with antibiotic properties, which he dubbed penicillin. This serendipitous observation began the modern era of antibiotic discovery. The development of penicillin for use as a medicine is attributed to the Australian nobel laureate Howard Walter Florey.

However, several others reported the bacteriostatic effects of Penicillium earlier than Fleming. The first published reference appears in the publication of the Royal Society in 1875, by John Tyndall. Ernest Duchesne documented it in an 1897 paper, which was not accepted by the Institut Pasteur because of his youth. In March 2000, doctors at the San Juan de Dios Hospital in San José, Costa Rica published the manuscripts of the Costa Rican scientist and medical doctor Clodomiro (Clorito) Picado Twight (1887–1944). They reported Picado's observations on the inhibitory actions of fungi of the genus Penic between 1915 and 1927. Picado reported his discovery to the Paris Academy of Sciences, yet did not patent it, even though his investigations started years before Fleming's.

Fleming recounted that the date of his breakthrough was on the morning of Friday, September 28, 1928. It was an example of fortuitous accident: In his laboratory in the basement of St. Mary's Hospital in London (now part of Imperial College), Fleming noticed a petri dish containing Staphylococcus plate culture he'd mistakenly left open, which was contaminated by blue-green mould. There was a halo of inhibited bacterial growth around it. Fleming concluded that the mould was releasing a substance that was repressing the growth and lysing the bacteria. He grew a pure culture and discovered that it was a Penicillium mould, now known to be Penicillium notatum. Charles Thom, an American specialist working at the U.S. Department of Agriculture, was the acknowledged expert, and Fleming referred the matter to him. Fleming coined the term "penicillin" to describe the filtrate of a broth culture of the Penicillium mould. Even in these early stages, penicillin was found to be most effective against Gram-positive bacteria, and ineffective against Gram-negative organisms and fungi. He expressed initial optimism that penicillin would be a useful disinfectant, being highly potent with minimal toxicity compared to antiseptics of the day, and noted its laboratory value in the isolation of "Bacillus influenzae" (now Haemophilus influenzae). After further experiments, Fleming was convinced that penicillin could not last long enough in the human body to kill pathogenic bacteria, and stopped studying it after 1931. He restarted clinical trials in 1934, and continued to try to get someone to purify it until 1940.