In which type of infection, the organisms that are normally commensals in the human become pathogenic when the body's immune defenses are compromised?

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2019

Explanation

An opportunistic infection is defined as an infection caused by microorganisms that are normally harmless (commensals) but become disease-causing (pathogenic) when the host's immune system is weakened.
The key elements are the presence of a commensal organism and a host with compromised immune defenses.
Conditions that can lead to a compromised immune system include HIV/AIDS, chemotherapy, long-term steroid therapy, and organ transplantation.
Examples of opportunistic pathogens include Candida albicans (causing thrush) and Pneumocystis jirovecii (causing pneumonia in AIDS patients).

Option A: An epornithic infection refers to a disease outbreak within a bird population.
Option B: An epizootic infection is a disease outbreak in an animal population, not necessarily related to the host's immune status.
Option C: A nosocomial infection is one that is acquired in a hospital or healthcare facility, regardless of the patient's immune status. While an immunocompromised patient can get a nosocomial infection, the term itself defines the location of acquisition, not the mechanism related to immunity.

Clinical Relevance

Nursing practice connection: Knowing Definitions of different types of infections based on epidemiology and host-pathogen interaction helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Recognizing patients at risk for opportunistic infections (e.g., those on chemotherapy, with HIV, or post-transplant) is a critical nursing responsibility for proactive monitoring and prevention.
Nursing care for immunocompromised patients involves meticulous infection control, including strict hand hygiene, aseptic techniques for invasive procedures, and potentially protective (reverse) isolation.
Patient education is vital. Nurses must teach patients and their families to recognize early signs of infection (like fever, cough, or new pain) and to avoid potential sources of infection (like raw foods or crowds).

How to Approach the Question

First, analyze the question stem to identify the key defining characteristics. The keywords are 'normally commensals', 'become pathogenic', and 'immune defenses are compromised'.
This combination of characteristics points to a specific mechanism of infection where the host's condition is the trigger.
Next, evaluate each option against these keywords.
Option A (Epornithic) and B (Epizootic) relate to animal/bird populations, which doesn't match the human context.
Option C (Nosocomial) relates to the location (hospital) where an infection is acquired, not the host's immune status as the primary cause.
Option D (Opportunistic) perfectly matches the definition: an organism takes the 'opportunity' of a weak immune system to cause disease. This makes it the correct answer.

Concept Tested & Keywords

Concept Tested: Definitions of different types of infections based on epidemiology and host-pathogen interaction.
Stem keywords: infection, commensals, pathogenic, immune defenses compromised
Lead-in keywords: In which type
Negative lead-in flag: false

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 87-89

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