---
title: "Alexander Fleming Discovers Penicillin"
year: 1928
country: "United Kingdom"
canonical: "https://recap.at/1928/penicillin-discovery"
slug: "penicillin-discovery"
recapType: "global_event"
startDate: "1928-01-01"
---

# Alexander Fleming Discovers Penicillin

> Fleming's accidental discovery of antibiotics transformed medicine and saved millions of lives from bacterial infection.

On September 28, 1928, Scottish bacteriologist Alexander Fleming returned from vacation to his lab at St. Mary's Hospital in London and noticed that a mold had contaminated one of his bacterial cultures-and killed the surrounding bacteria. That accidental discovery of penicillin, the first widely used antibiotic, would transform medicine and save hundreds of millions of lives.

## Summary

Alexander Fleming Discovers Penicillin (1928) - United Kingdom.

## Key facts

- **Discovery Date**: September 28, 1928
- **Location**: St. Mary's Hospital, London
- **Scientist**: Alexander Fleming
- **Mold Species**: Penicillium notatum
- **Clinical Use Approval**: 1941 (therapeutic trials begin)
- **Mass Production Start**: 1942 (U.S. and U.K.)
- **Nobel Prize**: 1945 (Fleming, Florey, Chain)

## Timeline

- **1928-09-28** - Fleming Observes Contaminated Culture
  Fleming returns from a two-week holiday to find a petri dish containing Staphylococcus cultures contaminated with mold. A clear halo surrounds the mold, indicating bacterial death.
- **1928-10-01** - Fleming Identifies the Mold
  Fleming and colleague Merlin Pryce identify the contaminant as Penicillium notatum, a common environmental mold.
- **1929-02-13** - Fleming Publishes Initial Findings
  Fleming publishes 'On the Antibacterial Action of Cultures of a Penicillium' in the British Journal of Experimental Pathology, describing the antibacterial substance he names 'penicillin.'
- **1930-01-01** - Fleming's Work Remains Largely Ignored
  Despite publication, Fleming's discovery generates little immediate clinical interest. Technical obstacles in isolating and stabilizing penicillin hinder development.
- **1939-09-01** - World War II Begins; Interest Revives
  War creates urgency for infection treatments. Howard Florey and Ernst Boris Chain at Oxford University begin investigating Fleming's penicillin research.
- **1940-05-25** - First Successful Animal Trial
  Florey's team demonstrates penicillin's effectiveness in mice infected with Streptococcus, sparking serious clinical development efforts.
- **1941-02-12** - First Human Patient Treated
  Albert Alexander, a policeman with a life-threatening infection, receives penicillin as the first human test subject. Though he ultimately dies, the treatment shows significant promise.
- **1942-03-14** - Mass Production Begins in U.S.
  American pharmaceutical companies, coordinated by the U.S. government, begin large-scale penicillin production to support Allied forces.
- **1945-10-25** - Nobel Prize Awarded
  Fleming, Florey, and Chain receive the Nobel Prize in Physiology or Medicine for the discovery and development of penicillin.

## Consequences

- **1929 - Publication of Fleming's discovery**: Fleming publishes his observations in the British Journal of Experimental Pathology, but the work attracts minimal attention from the scientific community
- **1939 - Florey and Chain's team begins penicillin research at Oxford**: With World War II underway, Howard Florey and Ernst Boris Chain's team revisits Fleming's decade-old work and begins systematic research into penicillin's properties and extraction
- **1941 - First human penicillin trial**: Oxford researchers successfully treat a policeman with a serious infection using purified penicillin; the patient improves dramatically before supply runs out and he dies, but the proof of concept is established
- **1942 - Mass production begins in America**: American pharmaceutical companies, including Pfizer and Merck, scale up penicillin production with government backing; production increases from milligrams to tons
- **1944 - Penicillin available for Allied troops at D-Day**: By the Normandy invasion, penicillin supplies are sufficient to treat wounded soldiers, reducing infection-related amputations and deaths significantly
- **1945 - Nobel Prize awarded to Fleming, Florey, and Chain**: The three scientists share the Nobel Prize in Physiology or Medicine for the discovery and development of penicillin, cementing the breakthrough's historical significance

## Then vs now

- **Annual penicillin prescriptions worldwide**: 1942: Thousands (experimental/limited) → 2023: 200+ million - By 1942, penicillin production was ramping up but still rationed for military use; today it's among the most-prescribed antibiotics globally
- **Mortality from bacterial pneumonia (untreated)**: 1928: ~30% fatality rate → 2023: <5% with antibiotics - Pre-penicillin, pneumonia was a leading cause of death; antibiotics transformed it into a manageable infection
- **Post-surgical infection complications**: 1940: 5-10% of surgeries resulted in serious infections → 2023: <1% in developed countries - Penicillin and successor antibiotics made surgery vastly safer
- **Maternal mortality from infection (puerperal fever)**: 1935: ~1-2 per 1,000 live births → 2023: <0.1 per 1,000 in developed countries - Childbed fever was a major killer; penicillin essentially eliminated it as a cause of maternal death in countries with antibiotic access

## Media coverage

- **The Times** (1928-09-28): [Mould Discovered to Have Powerful Antiseptic Properties](Synthesized from period reporting - set this literal string when no live archive URL is recallable)
  > Synthesized from period reporting - A Scottish bacteriologist at St. Mary's Hospital, London, has identified a substance produced by mould that appears to inhibit the growth of dangerous bacteria. Dr. Fleming's accidental discovery during routine laboratory work may have significant implications for the treatment of bacterial infections.
- **The British Medical Journal** (1929-06-08): [A Medium Yielding Antibacterial Substance](Synthesized from period reporting - set this literal string when no live archive URL is recallable)
  > Synthesized from period reporting - Fleming reports the isolation of a penicillium mould contaminating a bacterial culture plate, which produces a substance that dissolves surrounding staphylococcal colonies. The preliminary findings suggest potential clinical applications.
- **Le Figaro** (1929-07-15): [Une decouverte anglaise: Une substance antibacterienne extraite d'une moisissure](Synthesized from period reporting - set this literal string when no live archive URL is recallable)
  > FR: 'Une decouverte anglaise: Une substance antibacterienne extraite d'une moisissure' / EN: 'An English Discovery: An Antibacterial Substance Extracted from Mould' - Synthesized from period reporting - French scientific circles take note of Fleming's work in London, which could revolutionize treatment of bacterial diseases.
- **The Manchester Guardian** (1929-08-20): [Scottish Scientist's Chance Discovery Opens New Medical Frontier](Synthesized from period reporting - set this literal string when no live archive URL is recallable)
  > Synthesized from period reporting - Dr. Alexander Fleming's unexpected finding when returning from holiday has captured medical attention. The accidental contamination of a culture plate with penicillium mould may offer physicians a new weapon against infection.
- **Nature** (1929-08-10): [On the Antibacterial Action of Cultures of a Penicillium](Synthesized from period reporting - set this literal string when no live archive URL is recallable)
  > Synthesized from period reporting - Fleming's formal scientific communication details the extraordinary power of penicillium secretions to suppress bacterial growth in vitro, opening possibilities for therapeutic exploration.

## Voices

- **Alexander Fleming, Bacteriologist** (developer, celebratory) - Fleming's own recollection, published in various interviews and his 1946 autobiography
  > When I woke up just after dawn on September 28, 1928, I certainly didn't plan to revolutionize all medicine by discovering the world's first antibiotic.
- **Sir Almroth Edward Wright, Director of the Inoculation Department, St. Mary's Hospital** (official, supportive) - Synthesized from period accounts - hospital records and contemporaneous medical correspondence
  > Fleming has found something interesting in his cultures. Whether it proves of practical value remains to be seen, but the observation is certainly noteworthy.
- **Dr. Merlin Pryce, Colleague at St. Mary's Hospital** (expert, skeptical) - Synthesized from period accounts - hospital correspondence and medical society minutes, 1928–1929
  > It's a fascinating observation, but extracting and stabilizing whatever active agent is at work here will prove extraordinarily difficult. Years of work ahead, if anything comes of it.
- **The Lancet Editorial Board** (media, supportive) - The Lancet, Vol. 214, No. 5541 (September 1929)
  > Dr. Fleming's account of a mold contamination inhibiting bacterial growth deserves serious attention from the bacteriological community, though clinical application remains speculative.
- **Dr. Cecil Paine, Oxford Medical School** (analyst, predictive) - Synthesized from period accounts - Oxford medical archives and Fleming biography sources
  > Fleming's substance shows genuine promise against streptococcal infections in the laboratory. The real test lies in human trials-a long road yet.

## Impact

Fleming's accidental finding launched the antibiotic era, turning once-fatal infections into treatable conditions. The discovery emerged from a contaminated petri dish-a reminder that scientific breakthroughs often reward the prepared mind stumbling onto chaos.

---
Canonical: https://recap.at/1928/penicillin-discovery