How penicillin was really discovered (not via an open window)

Penicillin was discovered by Alexander Fleming at St Mary’s Hospital in London in 1928, when he came back from a holiday to find a Penicillium mould growing on a dish of Staphylococcus bacteria, surrounded by a bacteria-free ring. He named the substance the mould released penicillin, but it took another twelve years, and a team in Oxford, to start turning it into a medicine.

The version many of us learned has spores drifting in through Fleming’s open laboratory window. A 2002 article in the Medical Journal of Australia dismissed that part as myth, stating that the windows were fixed shut. A reply in the same journal argued they could be opened with ropes and pulleys, but that a likelier route for the spore was a dumb-waiter shaft connecting to a mycology laboratory on the floor below. Either way, chance delivered a rare subtype of Penicillium to a scientist primed to notice it.

The road from mould to medicine ran through Oxford and Illinois:

Year	What happened
1928	Fleming sees the clear ring around the mould
1940	In Oxford, Howard Florey and Ernst Chain’s team infect eight mice with deadly streptococci; only the four also given penicillin survive
1941	Policeman Albert Alexander, 43, starts to recover, then dies when the supply runs out
Early 1940s	Production moves to the US; in Peoria, Illinois, a mould from a rotting cantaloupe yields six times more penicillin than Fleming’s strain
1943	There is enough penicillin for the Allied armed forces
1945	Fleming, Florey and Chain share the Nobel Prize in Physiology or Medicine

Fleming used his Nobel lecture on 11 December 1945 to issue a warning about antibiotic resistance that now reads as prophecy:

“There is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant.”