Sulfa drugs, the first of which, Prontosil, was discovered by Gerhard Domagk in 1932, are a group of synthetic drugs derived from sulfanilamide that are used to treat bacterial infections. They were commonly used by soldiers and medics in World War II to treat wounds on the battlefield.
Sulfa was carried in both powdered and tablet form. Although antibiotics such as penicillin would later replace sulfa drugs as a primary means of treating bacterial infections, sulfa drugs are still used today in parts of the world, and for certain diseases and afflictions.
Sulfa powder is seen prominently during Medic Wade's death, were his fellow soldiers are seen pouring it into his wounds.