In 1939, Rene Dubos isolated gramicidin, an antibiotic, from a common soil microbe. His discovery helps cure a mastitis outbreak in the Borden Company’s cow herd, including the famed Elsie, at the 1939’s World’s Fair.

Although a single intraperitoneal injection of gramicidin protected mice against fatal bacterial infections, the compound was toxic when administered intravenously and thus could not be used to treat systemic infections. Topical gramicidin, however, proved highly effective and was used during World War II to treat wounds and ulcers. Indeed, gramicidin is still an ingredient in some modern-day topical antibiotics.