Coming soon
Video walkthrough
We’re producing a short video for every module — check back soon.
Exam category: Patient Care → Infection Control
Why it matters: One of the most logic-based, memorizable sections on the exam. Once you understand the chain of infection, precaution categories become intuitive instead of a memorization slog.
Every infection follows the same six-link chain. Break any one link, and you stop transmission. Everything else — hand hygiene, PPE, sterile technique, isolation categories — exists to break that chain at a specific point.
Pathogen → Reservoir → Portal of exit → Mode of transmission → Portal of entry → Susceptible host.
Breaking the chain at any single link stops transmission — you don't need to address all six. Hand hygiene breaks the "mode of transmission" link; sterilizing equipment breaks the "reservoir" link; immunization protects the "susceptible host" link.
Modes of transmission:
| Term | Meaning |
|---|---|
| Disinfection | Reduces microorganisms; doesn't necessarily kill spores |
| Sterilization | Destroys ALL microorganisms including spores — required for anything entering sterile body cavities/bloodstream |
| Medical asepsis ("clean technique") | Reduces pathogen number/spread — handwashing, clean gloves |
| Sterile technique ("surgical asepsis") | Completely eliminates microorganisms from a field/instrument — invasive procedures |
Disinfection and sterilization are not interchangeable — equipment entering a sterile body cavity requires sterilization, not just disinfection.
Four sterilization methods, and one of them is the default. Steam sterilization in an autoclave — steam under pressure at high temperature — is the standard method for most surgical instruments and trays, and it's what you assume unless the item can't take heat and moisture. The other three exist to cover that exception: ethylene oxide gas for heat-sensitive items (electrical, plastic, rubber, optical), gas plasma, and chemical immersion. Chemical sterilization is the least satisfactory of the four — solution strength, temperature and immersion time are all hard to control, and contamination is hard to detect — so it isn't recommended when another method will do.
High-level disinfection is the in-between step, and the exam likes it. Chemical sterilants are used to achieve high-level disinfection for devices that touch mucous membranes but don't enter sterile tissue — a flexible fiberoptic endoscope is the standard example. It takes under an hour and destroys most microorganisms, but it does not kill spores. That last clause is the whole distinction: if spores survive, it is disinfection, not sterilization.
Memory cue — spores are the dividing line. Sterilization kills everything, spores included; autoclave is the default way to do it. High-level disinfection kills nearly everything but not spores — fast, chemical, and reserved for mucous-membrane devices like endoscopes.
Apply to every patient, every time, regardless of known infection status. Hand hygiene is the single most effective infection-control measure — before and after every patient contact, after glove removal, after contact with any contaminated surface.
Putting PPE on is a fixed order: gown → mask or respirator → goggles or face shield → gloves. The gown covers you from neck to knees and wraps around the back; the gloves go on last and are pulled over the gown's cuffs, so there's no gap at the wrist.
Taking it off is where people lose marks, and there is more than one right answer. Two removal sequences are both accepted:
| Sequence | |
|---|---|
| Option 1 | gloves → goggles/face shield → gown → mask or respirator |
| Option 2 | gown and gloves together → goggles/face shield → mask or respirator |
In Option 2 you grasp the gown at the front and pull away so the ties break, rolling it inside-out into a bundle, and peel the gloves off as you go — so your bare hands only ever touch the inside of the gown and gloves. That's the point of doing them as one movement: every contaminated surface ends up facing inward.
Whichever you use, two things hold: the mask or respirator always comes off last, grasped by the bottom ties then the top ones and never by the front (the front is contaminated). And all PPE comes off before you leave the room — except a respirator, which stays on until you have left and shut the door.
Perform hand hygiene immediately after removing all PPE, and again at any point during removal if your hands become contaminated.
Memory cue — gown on first, mask off last. Donning runs gown → mask → goggles → gloves. For doffing, remember what's dirty: glove outsides and the gown's front and sleeves, so those come off first (separately, or together rolled inside-out), and the mask/respirator is always last — and the respirator only after you're out of the room.
Safe injection practice: one needle, one syringe, one time — never reuse, never re-enter a medication vial with a used syringe.
Hand hygiene has two methods, and the exam tests when each one is required. An alcohol-based hand rub is the default between patients — it's faster (about 15 seconds versus a minute or more to reach a sink and wash) and dispensers are everywhere, which is exactly why compliance improves with it. Use it before and after patient contact, before donning gloves, after removing gloves, and after touching equipment near the patient.
But alcohol has a blind spot: it does not destroy bacterial spores. So it cannot replace soap and water in two situations:
When you do wash, scrub for at least 20 seconds with firm rotary friction, covering palms, backs of hands and between the fingers. Friction is doing more of the work than the soap is — it's the mechanical action that lifts organisms off the skin.
Memory cue — alcohol is fast but spore-blind. Rub for speed; wash when hands are visibly soiled or the bug is C. diff. Washing is 20 seconds, and friction, not soap, is what removes the organisms.
Once a sterile field is open, a short list of principles governs it, and exam items are almost always a direct application of one of them:
Memory cue — when in doubt, throw it out. Sterile technique has no partial credit: a contaminated field is replaced, not repaired. Remember the three geometry rules — 1-inch border, above the waist, never reach across.
Three destinations, and the exam wants you to sort items between them:
| Destination | What goes in it |
|---|---|
| Sharps container | Needles and syringes — placed in whole, never recapped |
| Biohazard-marked container (red bag) | Items carrying enough blood or body fluid to drip when squeezed |
| Regular waste | Everything else — including anything only lightly soiled, or where the blood or body fluid has dried |
The discriminator is the squeeze test, not the presence of blood. A dressing soaked enough to drip is regulated waste; a tissue with a dried spot on it is not. Biohazard bins are expensive to supply and dispose of, so the distinction is a real operational judgment rather than a formality — over-using them is a recognised problem, not a safe default.
Memory cue — squeeze it: does it drip? Drips → biohazard. Dried or lightly soiled → regular waste. Anything with a needle → sharps, un-recapped.
Used in addition to Standard Precautions when those alone aren't enough.
| Type | Example pathogens | PPE |
|---|---|---|
| Contact | MRSA, C. difficile, RSV | Gown + gloves |
| Droplet | Influenza, pertussis | Surgical mask |
| Airborne | TB, measles, varicella | Fit-tested N95+ respirator, ideally negative-pressure room |
A patient with suspected active TB needs an N95, not a surgical mask — because TB is airborne, not droplet. This exact substitution is a common trap.
Neutropenic precautions (reverse isolation) protect an immunocompromised patient from pathogens carried by staff/visitors — the opposite direction of standard isolation, which protects staff from the patient. PPE here protects the patient, not the technologist.
Healthcare-associated (nosocomial) infections — acquired during care, not present at admission. Radiology equipment (portable units, positioning sponges, lead markers, cassettes) is a documented potential vector if not properly disinfected between patients.
TB is airborne, not droplet — a surgical mask is insufficient regardless of how "routine" the exam seems; it requires a fit-tested N95 or higher. Also watch for reverse-isolation scenarios that try to get you to say the PPE protects the technologist — it protects the patient.
Source: Ehrlich, Patient Care in Radiography, 10th ed. Precaution categories cross-checked against CDC Standard and Transmission-Based Precautions guidance. The sterilization methods and the high-level-disinfection distinction (chemical sterilants, mucous-membrane devices such as flexible fiberoptic endoscopes, under an hour, spores survive) are Ehrlich Ch. 10–11, as are the sterile-field principles — the 1-inch perimeter buffer zone, keeping sterile items above waist level and in sight, never reaching across the field, and discarding rather than salvaging a suspected item. Hand-hygiene specifics are Ehrlich Ch. 10: the 20-second scrub with rotary friction, the CDC alcohol-rub guidance, and the rule that alcohol cannot destroy spores such as C. difficile, so soap and water is required when hands are visibly soiled or spores are involved. The waste rule — objects contaminated with enough blood or body fluid to drip when squeezed go in a biohazard-marked container, while small amounts of dried blood do not — is Ehrlich Ch. 10, as is the un-recapped sharps container.
Ready for the module check?
5 questions, freshly drawn each attempt. 85%+ to pass. Retries are unlimited and immediate.