The Mould That Saved Millions

Not so long ago, a small cut could kill you.

Before the 1940s, there were no antibiotics. If bacteria got into a wound, there was little a doctor could do. Infections that are easy to treat today, such as pneumonia, blood poisoning or an infected scratch from a rose thorn, killed huge numbers of people, young and old. In war, many more soldiers died from infected wounds than from the injuries themselves.

The untidy laboratory

Alexander Fleming was a Scottish scientist who worked at St Mary's Hospital in London. He studied bacteria, and he was famous for being brilliant, and for having a rather untidy laboratory.

In the summer of 1928, he went away on holiday. Before he left, he stacked some glass dishes, called Petri dishes, on a bench. They contained colonies of Staphylococcus, bacteria that cause boils and serious infections.

When he came back in early September, he began sorting through the dishes. On one of them, he noticed something strange. A blob of blue-green mould had grown on it, probably from spores that had drifted in. And all around the mould, the bacteria had died. There was a clear ring, as if something from the mould was killing them.

Fleming was curious.

The juice

He grew the mould, which turned out to be a kind of Penicillium, in a liquid broth. He found that the broth, which he called "mould juice", killed many kinds of harmful bacteria, even when diluted many times. It did not seem to harm white blood cells. He named the active substance penicillin.

Fleming published his findings in 1929.

But there was a problem. Penicillin was very difficult to purify and very unstable. Fleming and his assistants could only produce tiny amounts, and it quickly lost its power. He was not a chemist, and he could not find a way to make enough of it to treat patients. For about ten years, penicillin was mostly forgotten, a scientific curiosity in an old journal.

Oxford

In 1938, at the University of Oxford, a team of scientists led by the Australian pathologist Howard Florey, together with the German-born biochemist Ernst Chain, began looking for natural substances that could fight bacteria. Chain found Fleming's old paper.

They decided to try to purify penicillin.

It was hard, slow work. The Second World War had begun, and there was little money and equipment. A brilliant biochemist on the team, Norman Heatley, invented ways to grow the mould and extract penicillin, using whatever he could find: milk churns, bathtubs, bedpans and specially made ceramic vessels. The laboratory became a small factory, staffed partly by young women known as the "penicillin girls".

In May 1940, they tested penicillin on mice infected with deadly bacteria. The mice that were not given penicillin died. The mice that were given it survived.

The first patient

In February 1941, they tried penicillin on a human being for the first time. Albert Alexander was a policeman in Oxford, who had developed a terrible infection, which had spread across his face and body after a scratch.

Within a day of receiving penicillin, he began to recover. His fever fell. He started to eat again.

But they did not have enough penicillin. They even collected it back from his urine to purify and use again. After a few days, the supply ran out. The infection returned, and Albert Alexander died.

The treatment had worked. They simply needed far more of it.

Mass production

Britain, at war, did not have the factories. So in 1941 Florey and Heatley flew to the United States. There, at a government laboratory in Peoria, Illinois, scientists found better ways to grow the mould in huge tanks. A search for stronger strains of Penicillium turned up a mouldy cantaloupe melon from a local market, which produced far more penicillin than Fleming's original strain.

American drug companies scaled up production rapidly. By the time of the D-Day landings in June 1944, there was enough penicillin to treat Allied soldiers wounded in the invasion of Normandy.

The Nobel Prize

In 1945, Alexander Fleming, Howard Florey and Ernst Chain shared the Nobel Prize in Physiology or Medicine for the discovery of penicillin and its use in treating infections.

In his Nobel lecture, Fleming warned that bacteria could become resistant to penicillin if it was misused. He was right. Antibiotic resistance is one of the biggest challenges in medicine today.

Penicillin and the antibiotics that followed it are estimated to have saved hundreds of millions of lives.

Want to read more?

Eric Lax's The Mold in Dr. Florey's Coat tells the full story of the Oxford team, whose work is less famous than Fleming's discovery but was just as important. The Nobel Prize website has free biographies of all three prizewinners and their Nobel lectures.