An infection in a patient with compromised defenses by an agent of low virulence that would not produce infection in a normal patient is known as?

Appeared in: NVS Staff Nurse - 2019

Explanation

An opportunistic infection is defined as an infection caused by a microorganism that ordinarily does not cause disease but becomes pathogenic when the host's immune system is impaired.
The key components described in the question—a host with 'compromised defenses' and a pathogen of 'low virulence'—are the defining characteristics of an opportunistic infection.
These pathogens take the 'opportunity' of a weakened immune system to cause disease, something they cannot do in a healthy, immunocompetent individual.
Examples include Candida albicans causing thrush in a patient on chemotherapy or Pneumocystis jirovecii pneumonia (PCP) in a person with AIDS.

Option B: An iatrogenic infection is one that results from a medical intervention or treatment, such as a surgical procedure or catheterization. The defining factor is the medical action, not the host's immune status.
Option C: A subclinical (or asymptomatic) infection is one where the host is infected but shows no observable signs or symptoms of the disease. This term describes the clinical presentation, not the relationship between host immunity and pathogen virulence.
Option D: A nosocomial infection is defined by where it is acquired—specifically, in a hospital or other healthcare facility, typically appearing 48 hours or more after admission. While an opportunistic infection can be nosocomial, the term itself refers to the location of acquisition, not the host's condition.

Clinical Relevance

Nursing practice connection: Use the key finding related to Classification of Infections to guide bedside assessment, documentation, and the next nursing action.
Nurses must be vigilant in identifying patients at high risk for opportunistic infections, including those with HIV/AIDS, cancer patients on chemotherapy, organ transplant recipients on immunosuppressants, and individuals on long-term corticosteroid therapy.
Implementing protective measures, such as neutropenic precautions (strict hand hygiene, private room, no fresh flowers/fruits, and wearing a mask), is a critical nursing responsibility to shield these vulnerable patients.
What if? If a patient on chemotherapy develops a bloodstream infection from their central line while in the hospital, the infection would be classified as opportunistic (due to their compromised immunity), iatrogenic (caused by the invasive line), and nosocomial (acquired in the hospital). This shows how these categories can overlap.

How to Approach the Question

First, identify the core concepts in the question stem. The key phrases are 'compromised defenses' (weakened immune system) and 'agent of low virulence' (a microbe that is not usually harmful).
Next, analyze the meaning of each option.
Evaluate 'Opportunistic infection'. The word 'opportunity' implies taking advantage of a special situation. This aligns perfectly with a weak microbe causing disease only when the host's defenses are down.
Contrast this with the other options. 'Iatrogenic' relates to medical treatment, 'subclinical' to a lack of symptoms, and 'nosocomial' to the hospital setting.
Conclude that 'Opportunistic infection' is the only term that specifically describes the relationship between a compromised host and a low-virulence pathogen.

Concept Tested & Keywords

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) pp. 87-89, 88-90

Practise the full NVS Staff Nurse - 2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.