How Alexander Fleming discovered penicillin

Ear ache? Sore throat? Tooth ache? If you’re suffering these symptoms, it's possible you'd benefit from a dose of penicillin.

And if that’s the case, you should be raising a glass to Sir Alexander Fleming, who discovered the popular antibiotic. He was born on 6 August 1881 in the small town of Darvel, Scotland.

Sir Alexander Fleming, courtesy of the Wellcome Library, London(CC BY-SA)

Penicillin is a naturally occurring substance, which is why we credit Fleming with discovering rather than inventing it. And to be absolutely correct, he re-discovered it three decades after a French medical student first made note of it. And, what’s more, the discovery came after Fleming left a petri dish out in the lab by accident!

In 1928, Fleming noticed that a blue-green mould had contaminated another specimen in the lab (the unwashed petri dish) and that bacteria on the dish were being dissolved.

He experimented with the mould and found that it killed a number of disease-causing bacteria. He named it penicillin and published his findings in 1929.

First page of Alexander Fleming's paper on penicillin, Wellcome Collection, CC BY

Despite this great discovery, penicillin wasn’t widely used straightaway.

After undergoing clinical trials in 1943, it was first used on a large scale during World War Two to treat soldiers wounded on D-Day. It wasn’t until 1948 that Andrew J Moyer, one of the scientists responsible for this progress, was granted a patent for a method for penicillin mass production.

Needless to say, the significance of penicillin was soon recognised. In 1945, the Nobel Prize in Physiology or Medicine was awarded jointly to Sir Alexander Fleming, Ernst Boris Chain and Sir Howard Walter Florey, 'for the discovery of penicillin and its curative effect in various infectious diseases'.

Early production of penicillin wasn’t exactly what we would call hi-tech – check out this photo of some equipment used. Yes, they’re old milk churns!

Equipment used for making early forms of penicillin, courtesy of Wellcome Collection (CC BY)

As is its way, nature always fights back, and only four years after drug companies began mass-producing penicillin, microbes that were resistant to it began appearing. Because of this growing resistance, penicillin is now less useful than it once was. Scientists continue to modify it and other antibiotics to try to keep one step ahead of the bugs and to keep us healthy.

Other discoveries thought to have come about by accident include: brandy – a side-effect of using distillation to make wine easier to transport; Teflon – an accidental chemical reaction when trying to make a new CFC; crisps (potato chips) – the result of a fed-up chef trying to outwit a complaining customer; and Viagra - its potent power was discovered when the drug was tested for its treatment of angina.