Infection Control Foundations
Master the chain of infection, standard precautions, hand hygiene, PPE selection, and aseptic technique, the core competencies that prevent healthcare-associated infections.
The Chain of Infection
Six links that must all be present for infection to occur
Infection requires an unbroken chain of infection (A conceptual model with six links: (1) infectious agent, (2) reservoir, (3) portal of exit, (4) mode of transmission, (5) portal of entry, (6) susceptible host. Breaking ANY link prevents infection.). Infection prevention strategies work by targeting the weakest links in this chain.
The Six Links
Hand Hygiene
The single most effective infection prevention measure
Hand hygiene prevents transmission by breaking the mode of transmission (The fourth link in the chain of infection. Contact transmission (direct and indirect via contaminated hands) is the most common mode in healthcare. Hand hygiene directly interrupts this transmission path.) link. Two methods are available, and the choice depends on the clinical situation.
Alcohol-Based Hand Rub (ABHR)
Preferred method for routine decontamination when hands are not visibly soiled. Faster, more effective against most organisms, less irritating to skin. Apply enough to cover all surfaces; rub until dry (minimum 20 seconds). NOT effective against: C. difficile spores and norovirus, these require soap and water.
Soap & Water Handwashing
Required when: hands are visibly soiled or contaminated with body fluids, after caring for patients with C. difficile or norovirus, before eating, after using the restroom. Technique: wet, apply soap, lather all surfaces for minimum 20 seconds, rinse, dry with paper towel, use towel to turn off faucet.
The 5 Moments for Hand Hygiene (WHO)
1. BEFORE touching a patient. 2. BEFORE a clean/aseptic procedure. 3. AFTER body fluid exposure risk. 4. AFTER touching a patient. 5. AFTER touching patient surroundings. These moments create a systematic approach to hand hygiene that covers all critical transmission opportunities.
Personal Protective Equipment (PPE)
Barrier protection matched to risk
PPE creates a barrier between the healthcare worker and infectious material. The critical principle is risk-based selection (PPE is selected based on the anticipated exposure: what body fluids might be encountered, what transmission route is involved, and what procedures will be performed. Using too little PPE creates risk; using too much wastes resources and creates a false sense of security.).
Gloves
Used when touching blood, body fluids, mucous membranes, non-intact skin, or contaminated items. Change between patients and between dirty and clean tasks on the same patient. Gloves do NOT replace hand hygiene, hands must be cleaned before donning and after removing gloves.
Gown
Protects skin and clothing. Required when anticipating contact with blood/body fluids that could soil clothing, or during contact precautions. Remove before leaving the patient's environment to prevent carrying organisms on clothing.
Mask & Eye Protection
Surgical mask: Protects against droplet transmission (within ~1 meter). N95 respirator: Required for airborne precautions (TB, measles, varicella), must be fit-tested. Eye protection (goggles/face shield): When splash or spray of body fluids is anticipated.
PPE Donning & Doffing Order
DONNING (putting on): Gown → Mask/Respirator → Goggles/Face shield → Gloves. DOFFING (removing): Gloves → Goggles/Face shield → Gown → Mask/Respirator. The doffing sequence is critical, the most contaminated items (gloves) come off first, and the mask (which protects airways) comes off last, AFTER leaving the patient area. Hand hygiene after each step of doffing.
Standard & Transmission-Based Precautions
The two tiers of isolation precautions
Infection prevention uses a two-tier system (Tier 1: Standard Precautions, applied to ALL patients regardless of diagnosis. Tier 2: Transmission-Based Precautions, added on top of standard precautions for patients with known or suspected infections transmitted by specific routes.).
Standard Precautions (ALL Patients)
Based on the principle that ALL blood, body fluids, secretions, excretions (except sweat), non-intact skin, and mucous membranes may contain transmissible infectious agents. Includes: hand hygiene, PPE based on anticipated exposure, respiratory hygiene/cough etiquette, safe injection practices, safe handling of contaminated equipment/surfaces.
Contact Precautions
For infections spread by direct or indirect contact (MRSA, VRE, C. difficile, scabies). Requires: private room or cohorting, gloves and gown for all interactions with patient or environment, dedicated equipment.
Droplet Precautions
For infections spread by large respiratory droplets (influenza, pertussis, meningococcal disease). Requires: private room, surgical mask within 1 meter, patient wears mask during transport.
Airborne Precautions
For infections spread by airborne droplet nuclei (TB, measles, varicella, COVID-19 aerosol-generating procedures). Requires: negative-pressure airborne infection isolation room (AIIR), N95 respirator (fit-tested), door closed at all times.
Match the Precaution Type
Terms
Definitions
Infection Control Quiz
1/20Which link in the chain of infection is MOST effectively targeted by hand hygiene?
Pre-nursing comprehensive review
1/20Which organelle contains its own DNA and is inherited exclusively from the mother?