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How did Joseph Lister apply Louis Pasteur’s germ theory to surgery?

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Painting by Albert Edelfelt showing Louis Pasteur in his laboratory, holding a glass flask and examining it intently, surrounded by scientific equipment on a workbench. — Louis Pasteur In the 19th century Louis Pasteur's work established the germ theory of disease, proving that microorganisms cause fermentation and sickness, which led to the development of pasteurization, aseptic techniques in medicine, and effective vaccines for diseases such as rabies. (Painting by Albert Edelfelt, 1885.)

Joseph Lister applied Louis Pasteur’s germ theory—which posited that microorganisms cause fermentation and putrefaction—to surgery by postulating that sepsis in surgical wounds was similarly caused by germs.12

To prevent these microorganisms from entering wounds, Lister pioneered antiseptic techniques designed to create a chemical barrier between the wound and the environment. His primary method involved using carbolic acid to sterilize surgical instruments, clean wounds, and disinfect the air and operating rooms.31

By adopting these practices, Lister successfully reduced surgical mortality rates significantly, demonstrating that controlling microbial exposure was essential for patient safety. Although his specific carbolic acid method is no longer in use, his fundamental principle—that bacteria must never gain entry into an operation wound—remains the cornerstone of modern surgery.123