In a world with no antibiotics, how did doctors treat infections?

The development of antibiotics and other antimicrobial therapies is arguably the greatest achievement of modern medicine. However, overuse and misuse of antimicrobial therapy predictably leads to resistance in microorganisms. Alternative therapies have been used to treat infections since antiquity, but none are as reliably safe and effective as modern antimicrobial therapy. So how were infections treated before antimicrobials were developed in the early 20th century?

Blood, leeches and knives

Bloodletting was used as a medical therapy for over 3,000 years. It originated in Egypt in 1000 B.C. and was used until the middle of the 20th century.

Medical texts from antiquity all the way up until 1940s recommend bloodletting for a wide variety of conditions, but particularly for infections. As late as 1942, William Osler’s 14th edition of Principles and Practice of Medicine, historically the preeminent textbook of internal medicine, included bloodletting as a treatment for pneumonia.