Bacteriologist Dr. Alexander Fleming returned from vacation to a St. Mary’s Hospital lab in London, England, in 1928 to discover two things: his workspace was a bit messy, to the point where microscopic mold had contaminated one of his petri dishes. The second was that the mold was Penicillin motum, and what it was doing to colonies of Staphylococcus aureus he had originally placed in the dish to study was like nothing he-or anyone-had seen before. This event would open the doors to the discovery of the world’s first antibiotic, penicillin. It took time, but in 1942 penicillin was used successfully to treat a civilian patient. By 1945 American companies were producing 650 billion units of the drug monthly, which today stands as the most widely used antibiotic in the world.
There's a fine line between "Oops!" and "Brilliant!" Nowhere is that more evident than when looking at some inventions that were purely happy accidents.