ABSTRACT
Both natural and synthetic antibiotics were discovered between the two World Wars. Penicillin was discovered by Alexander Fleming in 1928 and isolated in the late 1930s by a group led by Howard Florey. Gerhard Domagk’s group synthesized the first sulfa drug in 1932. After WWII, several important types of antibiotics were discovered including other β-lactams, aminoglycosides, macrolides, tetracyclines, and quinolones. Many semisynthetic derivatives were also introduced. Resistance to most antibiotics was noted within a few years and organisms resistant to multiple drugs appeared as well. The rate of discovery of new classes of antibiotics slowed after 1970.
