A secondary infection is an infection that occurs during or after treatment of another, already existing infection. It may result from the treatment itself or from alterations in the immune system.
For example, a vaginal yeast infection that occurs after antibiotic treatment of a bacterial infection is a secondary infection. The development of bacterial pneumonia following a viral upper respiratory infection is another example.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.