(I) Antibiotics are drugs that disable or kill infectious microorganisms. (II) However, for nearly every antibiotic that has been developed, a resistant strain of bacterium has appeared within a few decades. (III) Penicillin, for example, was originally isolated from a mold and has been widely prescribed since the 1940s. (IV) A revolution in human health rapidly followed its introduction, rendering many previously fatal diseases easily curable (such as strep throat and surgical infections). (V) During the 1950s, some doctors even predicted the end of human infectious diseases altogether.