Invasion of a susceptible host by a pathogen or microorganism, resulting in a disease is termed as:

Appeared in: UPUMS Nsg officer-2023

Explanation

Infection is the correct term describing the process where a microorganism invades a host, multiplies, and causes harm, leading to disease.
The key elements of an infection are the establishment of the pathogen within the host's tissues, its replication, and the subsequent host response that results in illness (SRC_26419).
This is distinct from colonization, where the microbe is present but does not cause disease.

Option A: Immunity is the host's defense against disease, not the disease process itself. It represents the body's ability to resist a pathogen.
Option B: Cross-infection describes the mode of transmission of a pathogen from one host to another, often in a healthcare setting. It doesn't define the disease process within a single host.
Option C: Colonization is the presence and multiplication of microorganisms on a host without causing tissue invasion or disease. It is a step that can precede infection but is not infection itself (SRC_26419).

Clinical Relevance

Nursing practice connection: Knowing Definitions of key terms in infectious disease microbiology helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding the difference between colonization and infection is crucial for nurses to avoid unnecessary antibiotic administration, which contributes to antibiotic resistance.
Nurses assess patients for signs and symptoms of infection (e.g., fever, redness, swelling, pain, elevated white blood cell count) to differentiate it from simple colonization.
This knowledge is fundamental to all infection prevention and control practices, such as hand hygiene, use of personal protective equipment (PPE), and environmental cleaning, to prevent cross-infection.

How to Approach the Question

First, read the question carefully to identify the key concept. The question asks for the term describing a pathogen invading a host and causing disease.
Analyze the keywords: 'invasion,' 'pathogen,' 'resulting in disease.' This points to an active disease process.
Evaluate each option based on its definition in microbiology.
Option A, 'Immunity,' is the host's defense, so it's incorrect.
Option B, 'Cross infection,' refers to transmission between hosts, not the process within one host.
Option C, 'Colonization,' means the microbe is present but not causing disease, which contradicts the question.

Concept Tested & Keywords

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E6 Medicine Davidson Principles Practice 24e p. 120-122

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