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Posted by on Apr 10, 2017 in Tell Me Why |

When Was Penicillin Discovered?

When Was Penicillin Discovered?

Penicillin was discovered in 1929 by Sir Alexander Fleming, then a professor and lecturer at the Royal College of Surgeons in London. He wanted to find a substance which would kill bacteria but would not also poison the tissues of the patient’s body. Fleming discovered penicillin by accident while he was researching into influenza.

He was examining a staphylococcus, a kind of germ, when he noticed that it had created a bacteria-free circle of mould around itself. When he experimented further, he discovered that this liquid mould, which he named penicillin, prevented further growth of the staphylococcus germ even when diluted and made 80 times weaker.

Also, penicillin had no poisonous effect on the human cells. Sir Alexander Fleming published his results in the Journal of Experimental Pathology in 1929. Fleming found that his “mold juice” was capable of killing a wide range of harmful bacteria, such as streptococcus, meningococcus and the diphtheria bacillus. He then set his assistants, Stuart Craddock and Frederick Ridley, the difficult task of isolating pure penicillin from the mold juice.

It proved to be very unstable, and they were only able to prepare solutions of crude material to work with. Fleming published his findings in the British Journal of Experimental Pathology in June 1929, with only a passing reference to penicillin’s potential therapeutic benefits. At this stage it looked as if its main application would be in isolating penicillin-insensitive bacteria from penicillin-sensitive bacteria in a mixed culture. This at least was of practical benefit to bacteriologists, and kept interest in penicillin going.

Others, including Harold Raistrick, Professor of Biochemistry at the London School of Hygiene and Tropical Medicine, tried to purify penicillin but failed. For some time it was thought that there was only one kind of penicillin, but later it was discovered that the mould could produce four penicillin’s. They were distinguished by the letters F, G, X and K. The best known is penicillin G, which came into widespread use after the Second World War.

It was Howard Florey, Ernst Chain and their colleagues at the Sir William Dunn School of Pathology at Oxford University who turned penicillin from a laboratory curiosity into a life-saving drug. Their work on the purification and chemistry of penicillin began in earnest in 1939, just when wartime conditions were beginning to make research especially difficult. To carry out a program of animal experiments and clinical trials the team needed to process up to 500 liters a week of mold filtrate.

They began growing it in a strange array of culture vessels such as baths, bedpans, milk churns and food tins. Later, a customized fermentation vessel was designed for ease of removing and, to save space, renewing the broth beneath the surface of the mold. A team of “penicillin girls” was employed, at £2 a week, to inoculate and generally look after the fermentation. In effect, the Oxford laboratory was being turned into a penicillin factory.

Meanwhile, biochemist Norman Heatley extracted penicillin from huge volumes of filtrate coming off the production line by extracting it into amyl acetate and then back into water, using a countercurrent system. Edward Abraham, another biochemist who was employed to help step up production, then used the newly discovered technique of alumina column chromatography to remove impurities from the penicillin prior to clinical trials.

In 1940, Florey carried out vital experiments, showing that penicillin could protect mice against infection from deadly Streptococci. Then, on February 12, 1941, a 43-year old policeman, Albert Alexander, became the first recipient of the Oxford penicillin. He had scratched the side of his mouth while pruning roses, and had developed a life-threatening infection with huge abscesses affecting his eyes, face, and lungs.

Penicillin was injected and within days he made a remarkable recovery. But supplies of the drug ran out and he died a few days later. Better results followed with other patients though and soon there were plans to make penicillin available for British troops on the battlefield.

Penicillin heralded the dawn of the antibiotic age. Before its introduction there was no effective treatment for infections such as pneumonia, gonorrhea or rheumatic fever. Hospitals were full of people with blood poisoning contracted from a cut or a scratch, and doctors could do little for them but wait and hope.

Content for this question contributed by Nicole Richardson, resident of Tampa, Hillsborough County, Florida, USA