In the chain of infection, an instrument contaminated with blood acts as a?

• A. Reservoir
• B. Vector
• C. Portal of exit
• D. Susceptible host

Answer: (A)

The main idea here is where pathogens can survive and be available to spread. An instrument contaminated with blood provides a place for pathogens to reside and persist, so it can act as a reservoir. This means the instrument can harbor infectious agents and potentially release them to another person if it’s not properly sterilized or handled.

It’s not a vector, because vectors are living organisms (like mosquitoes or ticks) that transmit pathogens between hosts. It’s not a portal of exit, which would be a route pathogens use to leave a host (such as blood from a wound or respiratory secretions). And it’s not a susceptible host, who would be the individual at risk of infection. By serving as a reservoir, the contaminated instrument becomes a source that can lead to transmission if the chain isn’t interrupted through proper sterilization and barrier precautions.