Raj. CHO -2025
Applied Microbiology & Infection control
Easy
Chain of infection is an interactive process that does not involve -
Appeared in: Raj. CHO -2025
Explanation
- The chain of infection model includes six specific components: infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host.
- Food is not a distinct link in this chain.
- Instead, contaminated food can serve as a 'vehicle' or 'fomite', which is part of the 'Mode of Transmission' link.
- Therefore, food is a means of transmission for certain pathogens but not a fundamental component of the chain itself.
Why Other Options Were Wrong
- Option A: The 'Host' (specifically, a susceptible host) is the final and essential link in the chain of infection. It is the organism that becomes infected by the agent.
- Option C: The 'Environment' is a crucial part of the chain as it often serves as the 'Reservoir'—the place where infectious agents live, grow, and multiply. Examples include contaminated water, soil, or surfaces.
- Option D: The 'Agent' (or infectious agent) is the first link in the chain of infection. It is the microorganism (bacterium, virus, etc.) that causes the disease.
Related Visual
- Visual 1: Diagram - A circular diagram illustrating the six links of the chain of infection in sequence: Infectious Agent -> Reservoir -> Portal of Exit -> Mode of Transmission -> Portal of Entry -> Susceptible Host, with an arrow leading back to the Infectious Agent to show the cycle.
Clinical Relevance
- Nursing practice connection: Knowing Components of the chain of infection helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
- Understanding the chain of infection is fundamental to nursing practice for preventing and controlling healthcare-associated infections (HAIs).
- Nurses break the chain through specific actions: hand hygiene (breaks transmission), using personal protective equipment (blocks portal of entry/exit), sterilizing equipment (eliminates agents/reservoirs), and promoting vaccination (reduces host susceptibility).
- What if? - If a patient is immunocompromised, the 'Susceptible Host' link is significantly weaker. Nursing care must then focus even more intensely on breaking other links, such as strict aseptic technique (blocking portal of entry) and placing the patient in isolation (interrupting transmission).
How to Approach the Question
- First, identify that the question is a 'negative' question, asking what is NOT part of a concept.
- Recall the six established links in the chain of infection: Agent, Reservoir, Portal of Exit, Mode of Transmission, Portal of Entry, and Susceptible Host.
- Evaluate each option against these six links.
- Option A, 'Host', corresponds to the 'Susceptible Host'.
- Option D, 'Agent', corresponds to the 'Infectious Agent'.
- Option C, 'Environment', often functions as the 'Reservoir'.
Concept Tested & Keywords
- Concept Tested: Components of the chain of infection
- Stem keywords: Chain of infection, interactive process
- Lead-in keywords: does not involve
- Negative lead-in flag: The question asks what is NOT part of the chain of infection.
Question ID
Q4G_qo3DtHbZc6QcM4V40p
Reference Book
Textbook of Applied Microbiology Including Infection Control and Safety (Second Edition) p. 234-235
Practise the full Raj. CHO -2025
Attempt every question from this paper in a timed mock, then review the full solution for each one.
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