Definition of Opportunistic microorganism
Opportunistic microorganism: A bacterium, virus, protozoan or fungus that takes advantage of certain opportunities to cause disease. Those opportunities are called opportunistic conditions. These microorganisms are often ones that can lie dormant in body tissues for many years, such as the human herpes viruses, or that are extremely common but usually cause no symptoms of illness. When the immune system cannot raise an adequate response, these microorganisms are activated, begin to multiply, and soon overwhelm the body's weakened defenses.
See also: Opportunistic condition, Opportunistic infection.Source: MedTerms™ Medical Dictionary
Last Editorial Review: 10/30/2013
Medical Dictionary Definitions A - Z
Search Medical Dictionary
eMedicineHealth Top News
Get breaking medical news.
Resources for Staying Well
- HIV-AIDS: Myths and Facts
- Understanding The Symptoms of AIDS/HIV
- The Top 10 Myths and Misconceptions About HIV and AIDS