Prontosil, the First Sulfa Drug, Begins the Antibiotic Age

In the early decades of the twentieth century, systemic bacterial infections frequently proved fatal. Physicians possessed effective chemical disinfectants and topical antiseptics for surface wounds, yet safe internal treatments remained almost non-existent. Medical therapies largely relied on vaccinations and rudimentary immunotherapy, while many practitioners remained skeptical that chemical agents could circulate harmlessly inside the human body while attacking living bacteria. This limited approach began to shift dramatically through work conducted within the industrial laboratories of Germany.

During the late 1920s and early 1930s, chemists Josef Klarer and Fritz Mietzsch at the Bayer laboratories of the IG Farben conglomerate pursued a systematic research initiative. They evaluated thousands of compounds related to synthetic azo dyes to assess their antimicrobial potential. By late 1932, Gerhard Domagk, who directed the laboratory testing, had found that one of these azo dyes protected mice against lethal infections caused by Streptococcus bacteria. IG Farben submitted a German patent application for the medical use of the drug on December 25, 1932. The drug's active core, a simpler compound later called sulfanilamide, had already been made years earlier by Paul Gelmo, a chemistry student in Vienna, who saw no medical use for it.