Science history: Alexander Fleming wakes up to funny mold in his petri dish, and accidentally discovers the first antibiotic — Sept. 28, 1928

On Sept. 28, 1928, Alexander Fleming woke up to check on his experiments investigating bacterial growth — and accidentally discovered the world’s first antibiotic.

The Scottish physicist and microbiologist had been doing experiments in a cramped, roughly 12-square-foot (1 square meter) room in a turret inside London’s St Mary’s Hospital. The famously untidy scientist would culture bacteria from infected hospital patients; he would leave those cultures around for two or three weeks until his bench was crammed with 40 to 50 plates. Then, he would inspect each plate to see if anything interesting had grown in it, before tossing it out.