Antibiotics Are Found in a Variety of Ways

Paul Ehrlich, Alexander Fleming, and Gerhard Domagk pioneered the development of antibiotics early in the Twentieth Century (see Box 3-1). Ehrlich made a variety of chemical derivatives that he examined to find ones that worked. Domagk followed in Ehrlich’s footsteps with the first agents that were widely used in clinical practice. Their general approach of testing many compounds has evolved into screening procedures that are now applied to hundreds of thousands of molecules. These methods, which are discussed in Chapter 9, “Making New Antibiotics,” are built on basic research that identifies potential drug targets.

Fleming found natural antibiotics. To obtain antibiotics from natural sources, samples from those sources are first incubated with a test microbe to determine whether the sample blocks growth. A positive sample is next split into parts with laboratory procedures that separate molecules into different test tubes for analysis. Eventually, the antibiotic molecules are isolated in pure form, and chemical analysis reveals the structure of the active form. Then medicinal chemists increase potency and safety by modifying the structure.