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Penicillin and antibiotics
September 1928 (Fleming); made a drug by Florey, Chain and Heatley 1940–44· Invention or discovery· Germs, drugs & genetics
Well documentedSolid records, physical evidence or scientific consensus.
Penicillin, a germ-killer made by a mold, became the first widely used antibiotic and began the era of curing bacterial infections.
See it on the Technology & Medicine map →How it works
In September 1928 Alexander Fleming, at St Mary's Hospital in London, noticed that a Penicillium mold had killed bacteria on a culture plate, but he could not purify it. In 1939–41 Howard Florey, Ernst Chain and Norman Heatley at Oxford extracted it and showed it cured infections in mice and then people. US labs and companies mass-produced it by deep-tank fermentation in time for D-Day in 1944. Antibiotics kill bacteria or stop their growth; they do not work on viruses.
Why it mattered
Infections from wounds, childbirth and pneumonia became curable. Antibiotics also made major surgery, chemotherapy and transplants far safer.
Think of it like
Molds make penicillin to keep rival bacteria off their patch, like a tenant with an exclusive-use clause.
How we know
Fleming's 1929 paper, the Oxford team's 1940 and 1941 papers in The Lancet, and wartime production records. Fleming, Florey and Chain shared the 1945 Nobel Prize.
Still unknown or debated
Fleming's lucky plate is hard to reproduce; the exact mold source, timing and temperatures that made it possible are still argued over.
Inside this (4)
Connections (4)
▸Germ theory of disease set the target for Penicillin and antibioticsMostly agreed
The connection
Once Pasteur and Koch showed that specific bacteria cause specific diseases, the goal became a drug that kills the germ without harming the patient. Fleming, a bacteriologist trained in that tradition, spotted penicillin because he was growing staph bacteria on culture plates, a technique developed in Koch's lab.
When and how
Paris and Berlin, 1860s–1880s (Pasteur, Koch); St Mary's Hospital, London, 1928 (Fleming).
How sure are we?
Fleming's 1929 paper describes penicillin stopping named bacteria on culture plates, using lab methods that came straight from germ theory.
Debates and open questions
Pasteur and others noticed in the 1870s that some microbes hold back others, but no one turned that into a drug for decades; why the gap lasted so long is discussed.
▸Penicillin and antibiotics was followed by Streptomycin and the cure for TBWell documented
The connection
René Dubos's gramicidin (1939) and penicillin's revival at Oxford (1940–41) showed that microbes make powerful germ-killers. Waksman, Dubos's former teacher, systematically screened thousands of soil microbes, with backing from the drug company Merck, and in 1943 his lab found streptomycin, which killed TB and other bacteria that penicillin could not.
When and how
Oxford, 1940–41; Rutgers University, New Jersey, 1939–43, where Waksman's lab also found actinomycin (1940) before streptomycin.
How we know
Lab papers and patent records show the sequence; Waksman popularized the word 'antibiotic' in the early 1940s, as penicillin's results made the field urgent.
Debates and open questions
Waksman had studied soil microbes for decades; historians weigh how much Dubos's gramicidin, penicillin's success and Merck's money each drove his search.
▸Penicillin and antibiotics was undermined by Antibiotic resistanceWell documented
The connection
Bacteria that survive a drug multiply and pass on their defenses. Penicillin-resistant staph, which makes an enzyme that breaks penicillin apart, spread within a few years of mass use. Nearly every antibiotic since has met the same fate, usually within years to a decade of its launch.
When and how
Hospitals in Britain, the US and elsewhere from the mid-1940s; by the 1950s most hospital staph infections resisted penicillin.
How we know
In 1940 Edward Abraham and Ernst Chain found a bacterial enzyme that destroys penicillin, before the drug was in use; hospital surveillance has tracked resistance since.
Debates and open questions
Resistance genes long predate medicine: bacteria in 30,000-year-old permafrost carry them. How much human overuse, versus natural spread, drives today's crisis is still studied.
▸Sulfa drugs were overtaken by Penicillin and antibioticsWell documented
The connection
Sulfa drugs proved that chemicals could cure infections inside the body, reviving interest in Fleming's neglected penicillin. Penicillin, purified from 1940, killed bacteria rather than just halting their growth, worked on more infections and was less toxic. By the late 1940s it had replaced sulfa drugs for most uses.
When and how
Germany and France, 1935–36 (sulfa drugs); Oxford, 1939–41 (Florey, Chain, Heatley); US mass production, 1943–45.
How we know
Historians such as John Lesch show that sulfa's success made drug cures credible and research fundable; wartime medical records show the switch.
Debates and open questions
Sulfa drugs never vanished: combinations such as trimethoprim-sulfamethoxazole are still widely used, so 'overtaken' describes most uses, not all.