Secondary infections
A secondary infection is an infection that occurs during or after treatment for another infection. It may be caused by the first treatment or by changes in the body or immune system that allow a second infection.
Two examples of a secondary infection are:
- A vaginal yeast infection after taking antibiotics to treat an infection caused by bacteria
- Pneumonia caused by bacteria or fungi after having an upper respiratory infection (like a cold) that was caused by a virus
Secondary infection occurs during or after treatment of a primary infection because the normal bacterial flora is destroyed, allowing yeast to flourish.
The immune system protects the body from potentially harmful substances. The inflammatory response (inflammation) is part of innate immunity. It occurs when tissues are injured by bacteria, trauma, toxins, heat or any other cause.
References
Clifton IJ, Ellames DAB. Respiratory medicine. In: Penman ID, Ralston SH, Strachan MWJ, Hobson RP, eds. Davidson's Principles and Practice of Medicine. 24th ed. Philadelphia, PA: Elsevier; 2023:chap 17.
Dockrell DH, Sundar S, Angus BJ. Infectious disease. In: Penman ID, Ralston SH, Strachan MWJ, Hobson RP, eds. Davidson's Principles and Practice of Medicine. 24th ed. Philadelphia, PA: Elsevier; 2023:chap 13.
Version Info
Last reviewed on: 8/26/2023
Reviewed by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
