opportunistic pathogen
Microorganism that typically causes disease only in immunocompromised hosts, serving as marker of underlying immune dysfunction.
Full Definition
An opportunistic pathogen is a microorganism that typically does not cause disease in immunocompetent individuals but can cause severe, life-threatening infections in immunocompromised patients. In pediatric immunology, the presence of infections with opportunistic pathogens such as Pneumocystis jirovecii, Candida species, cytomegalovirus, or atypical mycobacteria often signals underlying primary immunodeficiency. These organisms take advantage of defective host immune responses, and their identification in a pediatric patient should prompt thorough immunologic evaluation. The specific types of opportunistic infections can provide clues about which components of the immune system are defective.
Usage
Usage note: Infection patterns can indicate specific immune defects; requires high index of suspicion in pediatric patients.
In Context
- "The isolation of Pneumocystis jirovecii, an opportunistic pathogen, prompted urgent evaluation for primary immunodeficiency." — Infectious disease consultation
- "Multiple opportunistic pathogens were identified, suggesting severe compromise of both cellular and humoral immunity." — Clinical assessment