Ernest Duchesne: The Forgotten Discoverer of Penicillin

In 1897, a young French medical student named Ernest Duchesne submitted a ground-breaking doctoral thesis titled Contribution to the Study of Vital Competition Between Microorganisms: Antagonism Between Moulds and Microbes . In this work, Duchesne introduced a revolutionary idea that bacteria and moulds are locked in a constant struggle for survival, and this antagonism could be exploited for therapeutic use. Although the therapeutic properties of fungi and plants in treating infections was known since ancient times, it was Duchesne who showed experimentally that certain moulds destroyed pathogenic bacteria such as Salmonella typhi (which causes typhoid fever) and Escherichia coli in laboratory cultures and when injected into guinea pigs. What Duchesne had discovered was the natural antibiotic penicillin—an achievement typically credited to Scottish physician Alexander Fleming. Duchesne’s work remained largely forgotten until it was rediscovered more than 50 years later, in 1949, four years after Fleming was awarded the prestigious Nobel Prize for his discovery. Culture of penicillium mould. Photo credit: Wikimedia Commons Ernest Duchesne was born in Paris in 1874, the son of a chemical engineer who owned a tannery. After completing his secondary education, he was admitted to the military medical school in Lyon (École du Service de Santé Militaire) in 1894. Two years later, Duchesne began his research under the guidance of Gabriel Roux, a professor of microbiology and Director of the Municipal Office of Hygiene in Lyon. Roux had observed an intriguing phenomenon: despite the abundance of fungal spores in the air, they were absent in tap water and fountain water, though they could be made to grow in distilled water. This led Roux to suspect that certain microorganisms in the water might be inhibiting mould growth. He suggested Duchesne explore this idea as the foundation for his thesis.