3.1 Infection Prevention & Control

The Chain of Infection

Infection prevention and control (IPAC) is built on breaking the chain of infection — the six linked conditions a microorganism needs to spread. The links are (1) the infectious agent (bacterium, virus, fungus, or prion); (2) the reservoir where it lives (a person, water, equipment, or the environment); (3) the portal of exit (respiratory secretions, blood, feces, wound drainage); (4) the mode of transmission (contact, droplet, airborne, common vehicle, or vector); (5) the portal of entry (broken skin, mucous membranes, an invasive line); and (6) the susceptible host (an immunocompromised, very young, or elderly client). The practical nurse (PN) can interrupt any link, but the single most effective break — and the exam's favourite answer — is hand hygiene, which attacks the mode of transmission.

Routine Practices and Additional Precautions

In Canada, PHAC (the Public Health Agency of Canada) frames infection control as Routine Practices (elsewhere called standard precautions) plus Additional (Transmission-Based) Precautions. Routine Practices apply to every client, every interaction, all the time, based on the assumption that any body fluid may be infectious. They include a point-of-care risk assessment, hand hygiene, PPE selection matched to the anticipated exposure, safe sharps handling, and environmental cleaning.

Additional Precautions layer on top of Routine Practices for a specific organism:

A classic trap: a surgical mask does not protect against airborne nuclei — tuberculosis, measles, and chickenpox demand a fit-tested N95 and a negative-pressure room. Conversely, droplet organisms are too large to need an N95; a surgical mask within about 2 metres suffices.

Hand Hygiene: The Four Moments

Hand hygiene is the number-one preventive measure. Follow the 4 Moments for Hand Hygiene: (1) before initial client or environment contact, (2) before an aseptic procedure, (3) after body-fluid exposure risk, and (4) after client or environment contact. Alcohol-based hand rub (ABHR) with 70 to 90 percent alcohol is preferred for routine hand hygiene because it is faster and more effective against most organisms. The crucial exception: C. difficile (and other spore-formers such as norovirus) — alcohol does not kill spores, so you must use soap and water, whose mechanical friction physically removes spores from the hands.

PPE Donning and Doffing Sequence

Sequence errors self-contaminate, so memorize both orders. Donning (putting on): hand hygiene, then gown, mask or respirator, eye protection, gloves. Doffing (removing): gloves, eye protection, gown, leave the room, then mask or respirator, then hand hygiene. Gloves are removed first because they carry the highest bioburden; the mask or respirator comes off last, after leaving the room, so the airway stays protected the longest. Perform hand hygiene immediately after doffing, and again between steps if the hands become visibly soiled.

Asepsis and Sterile Technique

Medical asepsis (clean technique) reduces the number of organisms; surgical asepsis (sterile technique) eliminates them and is used for invasive procedures, sterile dressing changes, and urinary catheter insertion. Core sterile-field rules the exam tests: the outer 2.5 cm (1 inch) border of a sterile drape is considered unsterile; keep sterile items above waist level and in view at all times; never reach across a sterile field, because anything passing over it can shed organisms; and never turn your back on it. Moisture wicks microorganisms upward, so a wet field is a contaminated field and must be replaced.

Reprocessing: The Spaulding Classification

Reusable equipment is reprocessed according to the Spaulding classification, which matches the level of decontamination to infection risk:

• Critical items enter sterile tissue or the vascular system (surgical instruments, needles) and require sterilization.
• Semi-critical items touch mucous membranes or non-intact skin (endoscopes, respiratory equipment) and require high-level disinfection.
• Non-critical items touch only intact skin (blood-pressure cuffs, commodes) and require low-level disinfection or cleaning.

Cleaning to remove visible soil must always precede disinfection or sterilization, because organic material shields microorganisms.

Outbreak and ARO Management

Antibiotic-resistant organisms (AROs) such as MRSA and VRE are managed with contact precautions, dedicated equipment, and often cohorting — grouping clients who carry the same organism when single rooms are scarce. During a facility outbreak, the PN supports enhanced environmental cleaning, active screening and surveillance, staff cohorting, and possibly admission or visitor restrictions. Prompt recognition, accurate reporting to the IPAC team, and consistent use of the correct precautions protect the susceptible host and close the chain of infection at its weakest link.

Common Exam Traps

Several distractors recur across CPNRE and REx-PN infection-control items, and recognizing them saves easy marks:

• Hand hygiene before PPE, not after — always clean hands before donning gloves; contaminated hands under gloves defeat the purpose.
• N95 only for airborne — do not select an N95 for droplet organisms such as influenza; a surgical mask within 2 metres is correct, and reserving N95s appropriately preserves supply.
• Alcohol rub is not universal — for C. difficile and other spores, only soap and water works; the exam frequently pairs a spore-former with an alcohol-rub distractor.
• Contaminated moves toward clean — during doffing and dressing changes, always work from the least to the most contaminated area, and remove gloves before touching clean surfaces such as a chart or door handle.
• A needlestick is an exposure emergency — allow the site to bleed, wash with soap and running water, and report immediately for post-exposure prophylaxis assessment; never squeeze hard or delay reporting to finish the shift.

Carrying these rules into the exam turns most infection-control questions into quick, confident answers.