History of penicillin

• 1. Introduction

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  Penicillin's story does not begin in a London hospital in 1928. It begins in 1895, when Vincenzo Tiberio, an Italian physician at the University of Naples, examined moulds pulled from a water well in Arzano and concluded that they contained soluble substances capable of killing bacteria. That was more than three decades before Alexander Fleming noticed anything unusual in his own laboratory, yet Tiberio's work drew little attention and faded from view. Somewhere between that overlooked well water and a wartime scramble to mass-produce a wonder drug, a name got attached to almost the entire discovery, while the scientists who actually turned it into medicine argued for decades over who deserved the credit. What happened in the years between an ignored Italian paper and a shared Nobel Prize? And why did a mould that killed bacteria in a dish take more than a decade to reach a single human patient? The answers start with people other than the one usually given credit.

• 2. Long Before The Petri Dish

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  Cultures in Australia, China, Egypt, Greece and India each arrived independently at the same rough idea: certain fungi and plants could treat infections. Many of the organisms they relied on, including numerous species of mould, do produce antibiotics naturally, so the old remedies often worked even though nobody understood why. Ancient practitioners had no way to isolate or identify whatever was doing the killing.

  In 1923, Clodomiro Picado Twight, a Costa Rican scientist working at the Pasteur Institute, recorded the antibiotic effect of Penicillium mould. Researchers of that era lumped most Penicillium species together under the vague label P. glaucum. That makes it impossible now to confirm exactly which mould Picado observed, or whether penicillin caused what he saw.

  A year later, André Gratia and Sara Dath at the Free University of Brussels were testing how bacterial samples affected other bacteria. They found something similar by accident. In 1924, they discovered that supposedly dead Staphylococcus aureus cultures had been contaminated by a streptomycete. An extract from it could kill S. aureus, along with Pseudomonas aeruginosa, Mycobacterium tuberculosis and E. coli. Gratia named the substance "mycolysate." The following year the pair identified a killer mould capable of stopping B. anthracis. They published their results, identifying it as Penicillium glaucum, in Comptes rendus des séances de la Société de Biologie et de ses filiales. The paper drew little notice. Nobody grasped the mould's medical value, and Gratia's original samples were eventually lost. Three years later, working in London, Fleming would stumble onto much the same discovery without knowing any of this had already happened.

• 3. The Contaminated Plate

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  At St Mary's Hospital in London in 1928, Alexander Fleming was trying to replicate research from Trinity College Dublin on variations in Staphylococcus aureus cultures. Before leaving for a summer holiday with his family at The Dhoon, his country home in Barton Mills, Suffolk, he inoculated several culture plates. He left them on a corner of his table, out of the way. He returned to his laboratory on the 3rd of September. There, he and his former student Daniel Merlin Pryce found one plate with its lid open, contaminated by a blue-green mould. Bacteria near the mould had failed to grow, while colonies farther away looked normal, so Fleming concluded the mould itself was killing them.

  Fleming photographed the contaminated culture and grew the mould again in fresh plates. After four days it formed large colonies with the same bacteria-killing effect. Testing it against different bacteria, he found it killed Staphylococcus, Streptococcus and the diphtheria bacillus. It had no effect on the typhoid bacterium or on Haemophilus influenzae, then believed to cause influenza. On the 7th of March 1929, he named the mould juice "penicillin." In his 1945 Nobel lecture he explained that he had simply coined the word, just as "Digitalin" had been coined for a substance from the plant Digitalis.

  Fleming initially believed his mould was Penicillium chrysogenum, a species the American microbiologist Charles Thom had described in 1910. But the mycologist Charles John Patrick La Touche identified it instead as Penicillium rubrum, the name Fleming used in his published paper. Thom re-examined the specimen in 1931 and reclassified it as P. notatum, leaving Fleming's mould known under both names for years. The Seventeenth International Botanical Congress, meeting in Vienna in 2005, finally adopted P. chrysogenum as the official name. Whole-genome sequencing in 2011 showed the mould actually belonged to P. rubens, a species the Belgian microbiologist Philibert Biourge had described back in 1923.

  Fleming suggested in 1945 that spores had drifted in through his window facing Praed Street. His co-workers disputed this, since the window was normally kept shut and hard for him to reach. A more likely explanation pointed to a floor below, where La Touche kept his own mould cultures with the door often left open. Temperature mattered too. That August the lab ran below 20 degrees Celsius early on, ideal for the mould. It later warmed to 25 degrees, ideal for the bacteria to form visible colonies. Fleming was a bacteriologist, not a chemist, so he handed the chemistry to his student Stuart Craddock, then later recruited Frederick Ridley to continue it. Neither could isolate penicillin before both left for other jobs. Fleming reported his findings to the British Journal of Experimental Pathology on the 10th of May 1929. The article attracted little attention. It also contained a significant error, claiming penicillin was insoluble in ether and chloroform. Ridley and Craddock had actually shown it dissolved in ether, acetone, alcohol and water. Harold Raistrick confirmed penicillin's chemical instability in 1932, but requests for Fleming's mould samples kept tapering off for years afterward.

• 4. Oxford Takes Up The Puzzle

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  In 1939, Ernst Boris Chain brought a long-ignored study to his supervisor's attention at the Sir William Dunn School of Pathology at Oxford. Howard Florey, the Australian scientist running the school, decided the topic was worth pursuing. He assembled a team that included Edward Abraham, Mary Ethel Florey, Arthur Duncan Gardner, Norman Heatley, Margaret Jennings, Jean Orr-Ewing and Gordon Sanders. This kind of interdisciplinary collaboration was almost unheard of in Britain at the time. Chain later admitted that the idea of practical clinical use "did not enter our minds when we started."

  The Medical Research Council's Edward Mellanby approved the project in September 1939, allocating 250 pounds to launch it and roughly 300 pounds a year for salaries. The Rockefeller Foundation later added far more, after a visit from Henry M. "Dusty" Miller Jr in November 1939. It committed 5,000 US dollars a year for five years. Georges Dreyer, Florey's predecessor, had happened to keep a penicillin mould sample alive since 1930 for unrelated work, and it passed to the team through his assistant Campbell-Renton.

  The bedpan, of all things, turned out to be the ideal shape for growing mould at scale, after glass bottles laid on their sides proved impractical. It inspired custom ceramic vessels made by J. Macintyre and Company in Burslem. Norman Heatley tried adding sugars, salts, malts, alcohol and even marmite to boost the yield. None of it worked, until brewer's yeast cut the incubation time by a third. Extracting the penicillin meant filtering the liquid through parachute silk and acidifying it. The team then pulled it into a solvent, first ether, then the safer amyl acetate. Heatley then found that the same substance would pass back out of the solvent into water if the solution turned alkaline. He called the method "reverse extraction." Ernst Chain solved the final step, freeze-drying the water away to leave a dry brown powder, using a technique recently developed in Sweden.

  One Oxford unit, defined by Norman Heatley's new assay, marked the purity needed to produce a 25 millimetre bacteria-free ring on a nutrient plate. In 1943, Edward Abraham proposed that penicillin's structure contained a beta lactam ring. Dorothy Hodgkin confirmed this in 1945 using X-ray crystallography, work that would only later earn her a prize of her own.

• 5. From Mice To The Battlefield

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  At 11 in the morning on Saturday the 25th of May 1940, Howard Florey injected eight mice with a virulent strain of Streptococcus. He then gave four of them penicillin, in two different dosing patterns, and left the other four untreated. By 3:30 am the next morning, all four untreated mice were dead, while the treated ones survived, except for one that died two days later. Florey called the result "a miracle." Repeat trials with larger groups of mice, up to fifty at a time, kept confirming the pattern: control animals died within hours, treated ones survived for days or longer.

  On the 17th of January 1941, Charles Fletcher injected Elva Akers, a terminally ill cancer patient, with 100 milligrams of penicillin to test its safety; she suffered only a brief fever. The real test came with Albert Alexander, an Oxford policeman with a severe facial infection. It had grown so bad that surgeons removed one of his eyes to relieve the pain. Fletcher gave him 200 milligrams on the 12th of February, followed by 100 milligrams every three hours. Within a day his temperature dropped and his wounds began to improve. But the team could not produce enough penicillin to sustain the treatment, even after recovering some from his urine for reuse. Alexander relapsed in early March and died on the 15th. Florey shifted focus to children, who needed smaller doses. The next patients, including a 15-year-old named Arthur Jones and a labourer named Percy Hawkin with a carbuncle, recovered fully.

  By 1943, Ethel Florey was overseeing a wider trial covering 187 cases of sepsis, published in The Lancet that March. Rising success rates pushed the British War Cabinet to form a Penicillin Committee on the 5th of April 1943. Florey then carried the drug to North Africa himself, joining Brigadier Hugh Cairns on the 29th of June 1943 with a stockpile of 40 million units. Over the next two months the two men treated more than a hundred cases. Florey argued that wounds should be cleaned and sealed promptly, trusting penicillin to prevent the gas gangrene that would once have made that reckless. During the 1944-45 campaign in Western Europe, a disease that had killed 150 out of every 1,000 casualties in the First World War all but disappeared. Open fractures recovered at a rate better than 94 per cent.

• 6. The Race To Mass-Produce

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  Howard Florey and Norman Heatley flew to the United States on the 27th of June 1941. They smeared mould spores into their own coat pockets in case their sample vials got lost. American officials proved slow to act. Alfred Newton Richards, chair of the Committee for Medical Research, finally secured a suspension of antitrust rules on the 7th of December 1943. That let rival drug companies share penicillin data.

  At the Northern Regional Research Laboratory in Peoria, Illinois, Andrew J. Moyer replaced sucrose with lactose in the growth medium. He then added corn steep liquor, a cheap byproduct the lab was always looking to use. The change increased penicillin yield tenfold. Searching further afield, the NRRL's Kenneth Bryan Raper tested moulds from Chongqing, Bombay and Cape Town. But the best-performing strain of all turned up on a mouldy cantaloupe sold in a Peoria fruit market in 1943. Researchers later irradiated that strain, nicknamed NRRL 1951, with X-rays and then ultraviolet light to breed increasingly potent descendants. One eventually produced 550 milligrams of penicillin per litre.

  Pfizer was then a small New York firm known for citric acid. It adapted its fermentation tanks to grow the mould submerged in liquid, rather than on shallow trays. Vice president John L. Smith, whose own daughter had died from infection, poured the company's resources into the technique. Pfizer converted the Rubel Ice plant in Brooklyn into a full production plant, opening it on the 1st of March 1944. In March 1942, that same emerging supply chain reached Anne Sheafe Miller, who was dying of streptococcal septicaemia at Yale New Haven Hospital. A phone call released 5.5 grams of penicillin, flown in from Washington. Within 48 hours her fever of 106 degrees Fahrenheit broke. She lived until 1999. American output rose from 21 billion units in 1943 to more than 1,663 billion in 1944. Over the same years, the price the government paid per million units fell from 200 dollars in 1943 to just 6 dollars in 1945.

• 7. Credit And The Nobel Prize

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  Ernst Chain wanted to patent penicillin; Howard Florey refused, arguing the discovery should benefit everyone. Florey consulted Sir Henry Dale of the Wellcome Trust, who advised that patenting would be unethical, and the Medical Research Council's Edward Mellanby agreed. Andrew Moyer patented the American production and isolation methods anyway in 1945. He filed through the British Patent Office, since he could not patent his own government work. When Fleming learned of the resulting American patents, he was furious. He asked why a discovery he had "given free for the benefit of humanity" should become "a profit-making monopoly of manufacturers in another country." Glaxo later paid nearly 500,000 pounds in royalties between 1946 and 1956 for access to American fermentation techniques. The dispute helped push Britain to found the National Research Development Corporation in June 1948 to manage its own patents.

  The Times ran a story on the 27th of August 1942 about penicillin's curative power, and public credit began splitting unevenly from there. Fleming welcomed the attention, but Florey avoided it, telling his secretary to "send them packing" when reporters showed up at the Dunn School. Confusion between the mould juice and the finished drug let inaccurate accounts spread, crediting Fleming alone for work Florey's team had actually done. Neither Fleming nor St Mary's Hospital made much effort to set the record straight. The medical historian Bill Bynum later described it as a contrast between "an alert individual" making an isolated observation and "the exploitation of the observation through teamwork."

  A single 1943 nomination from biochemist Rudolph Peters covered Fleming and Florey, but the committee decided it needed more information. By 1945, thirteen of the first sixteen nominations mentioned Fleming. Rumours circulated that the prize might go to him alone, with quarter shares for Florey and Chain. On the 25th of October 1945, the Nobel Assembly split the Physiology or Medicine prize equally three ways. The citation read "for the discovery of penicillin and its curative effect in various infectious diseases." When the New York Times reported it as a win for "Fleming and Two Co-Workers," John Fulton demanded and received a correction. Dorothy Hodgkin received her own Nobel Prize in Chemistry in 1964 for determining penicillin's structure. She became only the third woman to win that prize, after Marie Curie in 1911 and Irène Joliot-Curie in 1935.

• 8. Derivatives And Resistance

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  The original penicillin only worked against a narrow range of bacteria and could not be taken effectively by mouth in its early oral form, penicillin V. Researchers at the Beecham Research Laboratories isolated 6-aminopenicillanic acid, or 6-APA, the chemical nucleus of penicillin, from Penicillium chrysogenum cultures in 1957. They published the finding in Nature in 1959. Because 6-APA could be modified by attaching different side chains, it opened the door to a family of semisynthetic penicillins. Ampicillin, introduced in 1961, became the first of these that could be taken orally and still work against both Gram-negative and Gram-positive bacteria. Methicillin followed in the UK in 1959, designed specifically to counter bacteria that had evolved resistance to earlier penicillins.

  In 1940, years before methicillin existed, Ernst Chain and Edward Abraham had already reported an E. coli strain that produced penicillinase, an enzyme that breaks penicillin down. Fleming himself warned in his 1945 Nobel lecture that an "ignorant man" might underdose himself with over-the-counter penicillin and make his own microbes resistant. The UK required a prescription for antibiotics starting in 1947, and the United States followed in 1951. Resistant Staphylococcus aureus, later known as MRSA, turned up in the UK in 1960, less than a year after methicillin's introduction. That timing suggests resistant strains had likely existed even earlier. A 1999 survey in the UK found that 39 per cent of people mistakenly believed antibiotics could cure colds or flu. Another 12 per cent thought antibiotics were the best available treatment for those illnesses, the same misunderstanding Fleming had tried to warn against decades earlier.