Infection Control

Overview

Infection Control hangs off one diagram, the chain of infection, and one practical fact: you only have to break one link. The six links run in the order the organism travels: infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host. Hand hygiene is the single most effective measure, because microbes are most commonly spread by human hands.

The transmission routes split on two distinctions the exam loves. A fomite is an inanimate carrier such as an image receptor or tabletop, and it moves organisms by indirect contact; a vector is a living carrier, either one that bites or one, such as a fly, that just carries the organism. A droplet is a wet particle that falls out of the air within a few feet (textbooks say about 3, though CDC has seen droplets reach 6 feet or more); airborne means evaporated residue that stays suspended, which is why rubella sits on the droplet list while rubeola is airborne.

Precautions come in two tiers. Standard Precautions apply to every patient and treat all body fluids except sweat as potentially infectious. On top sit three transmission-based categories: contact means gloves before entering the room, droplet means a surgical mask put on as you enter the room (3 feet is the older textbook trigger), and airborne means an N95 respirator plus a private negative pressure room with the door closed. C. difficile forms spores that survive alcohol gel, so the answer there is soap and water.

Asepsis divides on spores too. Medical asepsis reduces organisms as far as practical; surgical asepsis destroys organisms and their spores, and any procedure that penetrates body tissue requires it. PPE comes off in a fixed order: gloves first, mask or respirator last, and in an airborne room the respirator stays on until the door is closed behind you. If sterility is questionable, the item is not sterile.