The Serendipitous Spore
In September 1928, the bacteriologist Alexander Fleming returned to his laboratory at St. Mary's Hospital in London after a holiday. He found a stack of petri dishes he had been using to culture Staphylococcus aureus, a bacterium responsible for abscesses and sore throats. One dish had been accidentally contaminated with a fungus, and around this blob of mold was a clear, bacteria-free zone. Fleming realized that the mold was producing a substance that inhibited the bacteria's growth.
The fungus was identified as a member of the Penicillium genus, specifically a variant now known as Penicillium rubens. Fleming named the bacteria-killing substance "penicillin." He published his findings in the British Journal of Experimental Pathology in 1929, but the scientific community showed little interest. The primary challenge was isolating the active substance in a stable form; early attempts to do so failed, and penicillin was considered a laboratory curiosity for nearly a decade. Fleming himself was unable to purify the compound, and its therapeutic potential remained untapped.
From Lab Bench to Lifesaver
The work on penicillin was revived in 1939 at the Sir William Dunn School of Pathology at the University of Oxford. A team led by pathologist Howard Florey and biochemist Ernst Boris Chain began to investigate penicillin's properties. An important member of their team, biochemist Norman Heatley, developed a back-extraction technique that allowed them to purify penicillin in usable, though still limited, quantities.
On May 25, 1940, the team conducted an experiment: they infected eight mice with lethal doses of streptococci bacteria. Four of the mice then received penicillin injections. The next morning, the untreated mice were dead, while the four that received penicillin survived. This success led to the first human trial in February 1941. The patient, a police constable named Albert Alexander, showed remarkable improvement initially. The team's small supply of the drug ran out after five days, and he ultimately died from the infection.
The demands of World War II created an urgent need for antibacterial agents. Florey and Heatley traveled to the United States in 1941 to seek help with mass production. Collaboration with American pharmaceutical companies and the USDA's Northern Regional Research Laboratory in Peoria, Illinois, led to breakthroughs. A more productive strain of the mold, Penicillium chrysogenum, was found on a cantaloupe in a Peoria market. By the D-Day landings in June 1944, enough penicillin was being produced to treat all Allied casualties. For their work, Alexander Fleming, Howard Florey, and Ernst Chain shared the 1945 Nobel Prize in Physiology or Medicine.