In the chain of infection, link five is which concept?

• A. Portal of entry
• B. Reservoir
• C. Modes of transmission
• D. Susceptible host

Answer: (A)

The concept being tested is the route by which an infectious agent enters a new human host. In the chain of infection, after the pathogen leaves its reservoir and is transmitted to a new person, it must find a portal of entry to invade the body. The portal of entry is the entry point through which the organism penetrates defenses—such as breaks in the skin, or mucous membranes of the respiratory, gastrointestinal, genitourinary tracts, or invasive devices like IV lines. That’s why this link is described as portal of entry: it identifies how the agent gains access to the susceptible host. Preventing infections involves protecting these entry points with good wound care, aseptic technique, proper hand hygiene, and appropriate use of PPE to reduce the chance the organism can enter the body.