Louis Pasteur (1822–1895), Alexander Fleming (1881–1955)


In 1999, Time magazine stated that penicillin “was a discovery that would change the course of history.” It was the first of many antibiotics, or substances derived from microbes (fungi or bacteria) that kill or control the growth of other microbes. The earliest accounts of the healing properties of moldy bread appeared from ancient Egypt some 3,500 years ago in the Ebers Papyrus. In 1877, Louis Pasteur demonstrated that one microbe could be used to combat another and termed this antibiosis. He inoculated animals with a mixture of the anthrax bacillus and another common bacteria, which protected them against the deadly anthrax infection. Pasteur postulated that microbes released materials that might be used therapeutically, a prediction validated six decades later.

Alexander Fleming served in a battlefield hospital on the Western Front in France during World War I and observed that more soldiers were dying from antiseptics used to treat infected wounds than from the infected wounds. After the war, the Scottish-born Fleming resumed his bacteriological research at St. Mary’s Hospital Medical School in London. By 1928, when he turned his attention to the staphylococcus bacterium, he had gained the reputation as a well-respected scientist but one who did not maintain a neat laboratory.

After returning from a month-long family vacation in September 1928, he found that one of his culture dishes was contaminated and that there was no growth of staph colonies surrounding the fungal-contaminated growth. He astutely recognized what countless other scientists had overlooked: the fungus may have released an antibacterial substance. He grew a pure culture of the fungus, Penicillium notatum, and found that it selectively killed many, but not all, bacteria. He named this substance penicillin and in 1929 authored a paper that described its effects. Minimal interest was shown in his work until war clouds hung ominously over Europe in 1940, when penicillin’s potential was recognized and it was isolated and purified. Some sources estimate that penicillin saved the lives of millions of soldiers who would have died from infections of battle wounds. Accordingly, Fleming was a co-recipient of the 1945 Nobel Prize.

SEE ALSO: Prokaryotes (c. 3.9 Billion BCE), Fungi (c. 1.4 Billion BCE), Probiotics (1907), Bacterial Genetics (1946), Bacterial Resistance to Antibiotics (1967).

From a medical perspective, modern military history can be divided into the Infection Era (1775–1918) and the Trauma Era (1919–). On average, during the Infection Era, the ratio of infectious deaths to trauma deaths was 4:1. Thanks in part to penicillin; during World War II that ratio was reduced to 1:1. These photos depict military combatants serving on the Western Front during World War I.