13.1A: Origins of Antimicrobial Drugs

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The era of antimicrobials begins when Pasteur and Joubert discover that one type of bacteria could prevent the growth of another.

Learning Objectives

Recall the technical defintion of antibiotics

Key Points

Antibiotics are only those substances that are produced by one microorganism that kill, or prevent the growth, of another microorganism.
In today’s common usage, the term antibiotic is used to refer to almost any drug that attempts to rid your body of a bacterial infection.
The discovery of antimicrobials like penicillin and tetracycline paved the way for better health for millions around the world.

Key Terms

antimicrobial: An agent that destroys microbes, inhibits their growth, or prevents or counteracts their pathogenic action.
penicillin: Any of a group of broad-spectrum antibiotics obtained from Penicillium molds or synthesized; they have a beta-lactam structure; most are active against gram-positive bacteria and used in the treatment of various infections and diseases.

The history of antimicrobials begins with the observations of Pasteur and Koch, who discovered that one type of bacteria could prevent the growth of another. They did not know at that time that the reason one bacterium failed to grow was that the other bacterium was producing an antibiotic. Technically, antibiotics are only those substances that are produced by one microorganism that kill, or prevent the growth, of another microorganism.

Figure: **Alexander Fleming**: In 1928 Alexander Fleming observed antibiosis against bacteria by a fungus of the genus Penicillium and postulated the effect was mediated by an antibacterial compound, penicillin, and that its antibacterial properties could be exploited for chemotherapy.

The discovery of antimicrobials like penicillin by Alexander Fleming and tetracycline paved the way for better health for millions around the world. Before penicillin became a viable medical treatment in the early 1940s, no true cure for gonorrhea, strep throat, or pneumonia existed. Patients with infected wounds often had to have a wounded limb removed, or face death from infection. Now, most of these infections can be cured easily with a short course of antimicrobials.

The term antibiotic was first used in 1942 by Selman Waksman and his collaborators in journal articles to describe any substance produced by a microorganism that is antagonistic to the growth of other microorganisms in high dilution. This definition excluded substances that kill bacteria, but are not produced by microorganisms (such as gastric juices and hydrogen peroxide). It also excluded synthetic antibacterial compounds such as the sulfonamides. Many antibacterial compounds are relatively small molecules with a molecular weight of less than 2000 atomic mass units. With advances in medicinal chemistry, most of today’s antibacterials chemically are semisynthetic modifications of various natural compounds.