Infection prevention and control Study Guide

📖 Core Concepts Infection Prevention & Control (IPC): Practical branch of epidemiology aimed at stopping health‑care‑associated infections (HAIs) through hand hygiene, environmental cleaning, PPE, surveillance, isolation, and vaccination. Hand Hygiene: The single most effective, low‑cost measure; removes microorganisms from hands before they can be transferred to patients or surfaces. Hierarchy of Microbial Removal: Cleaning – mechanical/chemical removal of bulk microbes. Disinfection – kills all pathogens except bacterial spores. Sterilization – destroys all microorganisms, including spores. Spaulding Classification (SDSCS): Devices are grouped by infection risk → dictates required level of decontamination (critical → sterilize, semi‑critical → high‑level disinfect, non‑critical → intermediate/low‑level). Personal Protective Equipment (PPE): Physical barrier (gloves, gown, mask, eye protection) that shields health‑care workers from blood, body fluids, or aerosolized pathogens. Surveillance: Systematic review of patient data using CDC definitions to detect bloodstream, urinary, pneumonia, surgical‑site, or gastroenteritis infections. Isolation & Quarantine: Isolation – separates infected patients to stop spread (airborne, droplet, contact). Quarantine – separates suspected individuals until incubation ends or disease manifests. Outbreak Investigation: Process to confirm a true outbreak, find source/transmission, stop current cases, and prevent future ones. Vaccination of HCWs: Protects staff and patients; recommended vaccines include Hep B, influenza, COVID‑19, MMR, Tdap, varicella, meningococcal, etc. --- 📌 Must Remember Hand hygiene before/after every patient contact and after any contamination. Cleaning → Disinfection → Sterilization: follow the hierarchy; never skip a higher level when required. SDSCS Levels: Critical → Sterilize (steam autoclave, dry heat, chemicals, radiation). Semi‑critical → High‑level disinfection (e.g., glutaraldehyde). Non‑critical → Intermediate/low‑level disinfection (alcohol, hydrogen‑peroxide gas). Four autoclave parameters: adequate contact, temperature (≥121 °C), time (≥15 min at 121 °C), and moisture. PPE selection matches exposure risk: Blood/body fluid → gloves + gown + eye protection + mask. Airborne pathogen → N95/FFP2 respirator + gown + gloves. Surveillance impact: 32 % reduction in HAIs when robust surveillance + prevention are applied (SENIC study). Isolation type follows transmission route: Airborne → negative‑pressure room, N95 respirator. Droplet → surgical mask, spatial separation (≥1 m). Contact → gown + gloves, dedicated equipment. --- 🔄 Key Processes Hand‑Hygiene Procedure (WHO 7‑step soap wash): Wet hands → 2. Apply soap → 3. Palm‑to‑palm → 4. Right palm over left dorsum → 5. Left palm over right dorsum → 6. Interlace fingers → 7. Rinse & dry. Alcohol‑Based Hand Rub (5‑step): 1. Apply enough rub → 2. Rub palm‑to‑palm → 3. Palm‑to‑dorsum (each hand) → 4. Interlace fingers → 5. Rub thumbs & fingertips → let dry. Spaulding Classification Workflow: Identify device use → assign critical, semi‑critical, non‑critical → choose cleaning → disinfection → sterilization level accordingly. Steam Autoclave Cycle Verification: Load → ensure steam reaches all surfaces → run cycle (≥121 °C, ≥15 min) → check mechanical indicator → read chemical indicator tape → perform weekly biological indicator (spore) test. Surveillance Cycle: Define case criteria → data capture (chart review / software alerts) → classify infection type → report to infection‑control team → trigger intervention (isolation, education, environmental cleaning). Outbreak Investigation Steps (WHO): Verify outbreak → define case‑definition → construct epidemic curve → generate hypothesis (source, mode) → test hypothesis (environmental cultures, cohort study) → implement control measures → communicate findings. --- 🔍 Key Comparisons Cleaning vs. Disinfection vs. Sterilization Cleaning: removes debris; does not kill most pathogens. Disinfection: kills vegetative bacteria & viruses except spores. Sterilization: kills all microorganisms including spores. Critical vs. Semi‑critical vs. Non‑critical Devices Critical: contact with sterile tissue → sterilize. Semi‑critical: contact with mucous membranes/non‑intact skin → high‑level disinfection. Non‑critical: contact with intact skin → intermediate/low‑level disinfection. Isolation vs. Quarantine Isolation: for confirmed infectious patients. Quarantine: for suspected or exposed individuals until they are proven disease‑free. Airborne vs. Droplet vs. Contact Precautions Airborne: small particles → need negative‑pressure room + N95 respirator. Droplet: larger droplets → surgical mask + distance ≥1 m. Contact: direct/indirect touch → gown + gloves, dedicated equipment. --- ⚠️ Common Misunderstandings “Cleaning equals disinfection.” Cleaning only reduces load; does not guarantee pathogen kill. “Alcohol rub replaces hand washing always.” Alcohol is ineffective on visibly soiled hands; wash first. “All devices need sterilization.” Only critical devices; using higher‑level processes on non‑critical items wastes time/resources. “PPE is optional if hand hygiene is perfect.” PPE protects against splashes/ aerosols that hand hygiene cannot address. “Isolation rooms are needed for every infection.” Only for pathogens with airborne or droplet spread; many infections need standard precautions only. --- 🧠 Mental Models / Intuition “Hierarchy Ladder”: Visualize cleaning → disinfection → sterilization as climbing steps; you cannot skip a step when a higher level is required. “Risk‑Based Device Tree”: Think of a device’s patient contact as a branching tree; the closer to sterile tissue, the higher the branch → higher decontamination needed. “PPE as a Suit of Armor”: Each piece (gloves, gown, mask, eye shield) covers a specific “vulnerable surface”—if one piece is missing, the “armor” has a gap. “Surveillance as Early Warning Radar”: Continuous data scanning spots the “blip” of an outbreak before it becomes a wave. --- 🚩 Exceptions & Edge Cases Heat‑sensitive instruments (e.g., certain endoscopes) → cannot use steam autoclave; may require low‑temperature chemical sterilants or ionizing radiation. Alcohol rubs ineffective against Clostridioides difficile spores → must perform soap‑and‑water wash. Non‑critical devices that are difficult to clean (e.g., keyboards) → consider disposable covers or dedicated cleaning protocols. Patients with suspected airborne TB but negative smear → still place in airborne isolation until ruled out. --- 📍 When to Use Which Hand hygiene method: Use soap‑and‑water if hands are visibly dirty or C. difficile risk; otherwise, use alcohol‑based rub. Decontamination level: Critical: Steam autoclave unless item is heat‑sensitive → then chemical sterilant or radiation. Semi‑critical: High‑level disinfectant (e.g., glutaraldehyde) for endoscopes, laryngoscopes. Non‑critical: Alcohol wipes or hydrogen‑peroxide vapor for reusable items. PPE selection: Blood/body fluid exposure → gloves + gown + face shield + mask. Aerosol‑generating procedure → N95 respirator + eye protection + gown + gloves. Isolation type: Choose based on transmission route (airborne → N95 + negative pressure; droplet → surgical mask + spatial separation; contact → gown + gloves). --- 👀 Patterns to Recognize Repeated “before/after” hand‑hygiene checkpoints → any missed step signals a high‑risk moment. Device classification clues: “Contact with sterile tissue” → critical; “mucous membrane” → semi‑critical. Outbreak clues: Sudden spike in a single organism, clustering in a specific ward, or common procedure among cases. PPE breaches: Glove tears, exposed skin, or improper doffing → look for contamination spots near the face or clothing. --- 🗂️ Exam Traps Trap: “Alcohol rub kills all pathogens.” → Wrong; spores (e.g., C. difficile) are resistant. Trap: “All patient‑contact devices must be sterilized.” → Misleading; only critical devices need sterilization. Trap: “Isolation is required for every infectious patient.” → Incorrect; many infections are managed with standard precautions alone. Trap: “Hand washing is unnecessary if you wear gloves.” → False; gloves can be contaminated; hand hygiene before glove donning and after removal is essential. Trap: “If a device is labeled “reusable,” you can skip sterilization.” → Wrong; reuse does not waive the required decontamination level per its classification. ---