Printable — Microbiology
Chain of Infection Worksheet
Work through the six links in the chain of infection — define each one and write how nursing care breaks it. The single most important infection-control framework, on one page.
1 · Infectious agent
The pathogen that causes disease — bacteria, virus, fungus, parasite, or prion.
2 · Reservoir
Where the organism lives and multiplies — people, animals, water, soil, equipment, food.
3 · Portal of exit
How the organism leaves the reservoir — respiratory, GI, blood, skin/mucous membranes, GU.
4 · Mode of transmission
How it travels to the next host — contact (direct/indirect), droplet, airborne, vehicle, vector.
5 · Portal of entry
How the organism enters the new host — broken skin, mucous membranes, respiratory, GI, GU.
6 · Susceptible host
A person at risk — immunocompromised, very young or old, chronic illness, invasive lines.
Apex Nursing · apex-nursing.com — educational study aid. Verify infection-control practice against current CDC guidance and facility policy.
Educational use only. An educational study aid for learning infection-control principles. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.