What is an infectious agent?

• A. A pathogen that can cause disease, such as bacteria, viruses, fungi, parasites, or prions.
• B. A hospital bed
• C. A sterile instrument
• D. A disinfectant

Answer: (A)

An infectious agent is a pathogen capable of causing disease. It includes bacteria, viruses, fungi, parasites, and prions. These agents can invade a host, multiply, and disrupt normal bodily functions, leading to infection and illness. They spread through various routes—direct contact, respiratory droplets, contaminated surfaces, vectors—so infection-control practices focus on interrupting those transmission pathways.

The other items are not infectious agents themselves. A hospital bed is equipment that can become contaminated, a sterile instrument is free of pathogens, and a disinfectant is used to inactivate pathogens. They play roles in infection control but are not the agents that cause infection.