How did Joseph Lister reduce infections after surgery?

Joseph Lister revolutionized surgery by introducing antiseptic techniques to prevent sepsis, which was a leading cause of death in hospitals at the time.12

Influenced by Louis Pasteur’s germ theory, Lister recognized that microorganisms were responsible for infection. To combat this, he utilized carbolic acid to create a chemical barrier between the wound and the environment. His primary methods included:12

• Sterilization: He used carbolic acid to disinfect surgical instruments and the surgeon's hands.12
• Environmental Control: He applied the antiseptic to clean wounds and disinfect the air and the operating room.1

These practices were highly effective; between 1865 and 1869, surgical mortality in his ward dropped from 45 percent to 15 percent. While his specific carbolic acid methods are no longer used, his fundamental principle—that bacteria must be prevented from entering a surgical wound—remains the cornerstone of modern surgery.21