8.2 Infection Control, CDC Precautions, Spaulding Disinfection & PPE in HTM
Key Takeaways
- Healthcare-Associated Infections (HAIs) affect approximately 1 in 31 acute-care inpatients; breaking the chain of infection requires rigorous equipment hygiene, engineering controls, and barrier precautions.
- CDC isolation guidelines mandate Standard Precautions for all patients and three Transmission-Based Tiers: Contact (MRSA, VRE, C. diff; gloves/gown, dedicated equipment, bleach wipes for spores), Droplet (influenza, pertussis; surgical mask/face shield within 3–6 ft), and Airborne (TB, measles, COVID-19 aerosol; N95/PAPR, negative-pressure AIIR with 6–12 air changes/hr).
- The standard CDC sequence for donning PPE is Gown -> Mask/Respirator -> Goggles/Face Shield -> Gloves over cuff; the doffing sequence is Gloves -> Gown -> Goggles/Face Shield -> Mask/Respirator, followed immediately by hand hygiene.
- Earle Spaulding's Classification categorizes devices into Critical (enters sterile tissue/bloodstream; requires Sterilization via steam, EtO, or gas plasma), Semi-Critical (contacts mucous membranes/non-intact skin; requires High-Level Disinfection via glutaraldehyde, OPA, or peracetic acid), and Non-Critical (contacts intact skin; requires Low/Intermediate-Level Disinfection).
- High-Level Disinfection (HLD) with ortho-phthalaldehyde (OPA 0.55%, 12 min soak) or glutaraldehyde (2.4%, 20–45 min) destroys all vegetative microbes and viruses but requires verification via chemical test strips; for Clostridioides difficile spores, alcohol is ineffective, mandating sodium hypochlorite (bleach).
Last updated: August 2026
Infection Control, CDC Precautions, Spaulding Disinfection & PPE in HTM
Biomedical Equipment Technicians frequently service medical devices directly inside high-acuity clinical environments—including isolation rooms, operating suites, intensive care units, and endoscopy reprocessing suites. In doing so, technicians handle equipment that has been contaminated with blood, body fluids, respiratory droplets, and multi-drug resistant pathogens.
Failure to adhere to established infection prevention protocols not only jeopardizes the technician's health, but also risks cross-contaminating clean diagnostic equipment and transmitting lethal Healthcare-Associated Infections (HAIs) between patients. This section details the epidemiology, barrier precautions, personal protective equipment procedures, and chemical decontamination standards tested on the CBET exam.
1. Healthcare-Associated Infections (HAIs) & The Chain of Infection
According to the Centers for Disease Control and Prevention (CDC), on any given day, approximately 1 in 31 hospitalized patients suffers from at least one healthcare-associated infection. Medical devices frequently act as fomites (inanimate objects capable of carrying infectious organisms) if not properly cleaned and disinfected.
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| THE SIX-LINK CHAIN OF INFECTION |
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| [ 1. INFECTIOUS AGENT ] (Bacteria, Viruses, Fungi, Prions, Spores) |
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| v |
| [ 2. RESERVOIR ] (Patients, Staff, Biofilms on Infusion Pumps) |
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| v |
| [ 3. PORTAL OF EXIT ] (Blood, Respiratory Tract, Open Wounds) |
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| v |
| [ 4. MODE OF TRANSMISSION](Direct Contact, Droplets, Airborne Nuclei) |
| | |
| v |
| [ 5. PORTAL OF ENTRY ] (Surgical Incisions, IV Catheters, Mucosa) |
| | |
| v |
| [ 6. SUSCEPTIBLE HOST ] (Immunocompromised, Post-Op, Neonates) |
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| *** HTM BREAKS THE CHAIN AT LINK 4 (Transmission) & LINK 2 (Reservoir) ***|
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High-Consequence Pathogens in the Clinical Environment
- Methicillin-Resistant Staphylococcus aureus (MRSA): Gram-positive bacterium resistant to beta-lactam antibiotics; survives for weeks on dry hospital surfaces (keypads, patient monitor knobs, telemetry leads).
- Vancomycin-Resistant Enterococci (VRE): Highly persistent intestinal bacteria capable of surviving on medical plastics and bed rails for months.
- Clostridioides difficile (C. diff): Gram-positive, anaerobic, spore-forming bacterium causing severe pseudomembranous colitis. Bacterial endospores are impervious to alcohol-based hand sanitizers and standard quaternary ammonium wipes, requiring sporicidal sodium hypochlorite (bleach) or hydrogen peroxide.
- Mycobacterium tuberculosis (TB): Acid-fast bacillus transmitted via minute airborne droplet nuclei ($\le 5\text{ }\mu\text{m}$) that remain suspended in ambient air for hours.
- Bloodborne Viruses (HBV, HCV, HIV): Transmitted through percutaneous sharps injuries or mucosal splashes. Hepatitis B virus (HBV) remains viable and infectious on environmental surfaces for at least 7 days.
2. CDC Standard Precautions vs. Transmission-Based Precautions
The CDC establishes a two-tiered system of infection control: baseline Standard Precautions applied universally, supplemented by Transmission-Based Precautions tailored to specific pathogen transmission routes.
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| CDC TRANSMISSION-BASED PRECAUTION TIERS |
| |
| 1. CONTACT PRECAUTIONS 2. DROPLET PRECAUTIONS |
| Pathogens: MRSA, VRE, C.diff Pathogens: Flu, Pertussis, Meningitis |
| - Gown & Gloves mandatory - Surgical Mask within 3-6 ft of patient|
| - Dedicated patient equipment - Eye Protection (Goggles / Shield) |
| - Sporicidal bleach for C.diff - Standard room ventilation |
| |
| 3. AIRBORNE PRECAUTIONS |
| Pathogens: TB, Measles, Varicella, Disseminated Zoster, COVID Aerosols |
| - Negative Pressure Airborne Infection Isolation Room (AIIR) |
| - 6 to 12 Air Changes per Hour (ACH) with HEPA / Direct Exhaust |
| - NIOSH-Approved N95 Respirator (Fit-Tested) or PAPR Hood |
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Transmission-Based Precautions Comparison Matrix
| Precaution Tier | Target Pathogens & Clinical Conditions | Required PPE for Entry & Service | Room Engineering & Environmental Requirements | Equipment Servicing Protocol for BMETs |
|---|---|---|---|---|
| Standard Precautions | Universal baseline for all patients regardless of diagnosed infection | Gloves when contacting blood, bodily fluids, secretions, or broken skin; eye protection if splashing is anticipated | Standard positive/neutral pressure room; routine hospital environmental cleaning | Disinfect equipment between patients using hospital-approved intermediate germicide. |
| Contact Precautions | MRSA, VRE, C. diff, Norovirus, Scabies, draining abscesses, open colonized wounds | Isolation gown and clean nitrile gloves donned prior to entering patient room | Single-patient room preferred; dedicated non-critical equipment (BP cuff, stethoscope) | Wear full gown/gloves. Bag contaminated equipment in clear biohazard wrap before removing from room. Bleach wipes mandatory for C. diff. |
| Droplet Precautions | Influenza, Bordetella pertussis (whooping cough), Neisseria meningitidis, Mumps, Rubella | Surgical mask and eye protection (goggles or face shield) when within $3\text{--}6\text{ ft}$ of patient | Private room; spatial separation $>3\text{ ft}$; no special air handling/negative pressure required | Wear surgical mask and eye shield. Wipe all diagnostic tools and analyzers with germicidal wipes after exiting room. |
| Airborne Precautions | Mycobacterium tuberculosis (TB), Rubeola (Measles), Varicella (Chickenpox), Disseminated Zoster | NIOSH-approved N95 particulate respirator (annually fit-tested) or PAPR (Powered Air-Purifying Respirator) | Airborne Infection Isolation Room (AIIR): Negative air pressure differential ($\ge 2.5\text{ Pa}$ / $0.01\text{ inH}_2O$), $\ge 6\text{ ACH}$ (existing) or $\ge 12\text{ ACH}$ (new construction), HEPA filtration / outdoor exhaust | Minimize tool kit brought into AIIR. Check room negative pressure monitor before entry. Keep N95 mask sealed until completely outside room. |
3. Personal Protective Equipment (PPE): Donning & Doffing Protocols
The sequence of putting on (donning) and removing (doffing) PPE is critical. The CDC reports that most accidental self-contaminations occur during the doffing phase, when technicians inadvertently touch contaminated exterior PPE surfaces with bare hands.
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| CDC PPE DONNING & DOFFING SEQUENCES |
| |
| [ DONNING SEQUENCE ] (Putting On) [ DOFFING SEQUENCE ] (Taking Off)|
| 1. GOWN (Cover torso, tie neck/waist) 1. GLOVES (Glove-in-glove method)|
| 2. MASK / RESPIRATOR (Fit nose band) 2. GOWN (Pull away from neck/shldr)|
| 3. GOGGLES / FACE SHIELD (Adjust fit) 3. GOGGLES / FACE SHIELD (Strap) |
| 4. GLOVES (Extend over gown cuffs) 4. MASK / N95 (Bottom strap first)|
| 5. HAND HYGIENE (Immediate) |
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Step-by-Step Donning Protocol (Outside Patient Room)
- Gown: Unfold and slip arms into sleeves. Fully cover torso from neck to knees and wrap around back; securely tie at the neck and waist.
- Mask or N95 Respirator: Position over nose and mouth. Secure upper ties/band at crown of head, lower band at nape of neck. Mold the flexible metal nose strip firmly over the nasal bridge. For N95 respirators, perform a user seal check (inhale sharply to verify collapse; exhale gently to verify no perimeter leakage).
- Goggles or Face Shield: Position over brow and eyes; adjust head strap for secure fit.
- Gloves: Pull on gloves and extend the gauntlet cuff over the wrist cuff of the isolation gown to eliminate exposed skin gaps.
Step-by-Step Doffing Protocol (At Doorway or Anteroom)
- Gloves: The exterior of gloves is heavily contaminated. Using one gloved hand, grasp the outside edge of the opposite glove near the wrist and peel off, turning it inside out into a ball held in the remaining gloved hand. Slide bare fingers under the wrist band of the remaining glove, peel off inside out over the first glove, and discard into a biohazard container.
- Gown: Unfasten ties. Touching only the clean interior shoulders, peel the gown forward away from neck and shoulders. Turn the gown inside out as it is removed, roll into a tight bundle, and discard.
- Goggles or Face Shield: The front of the shield is contaminated. Grasp the rear elastic headband or ear rests with bare, clean hands and pull forward and away from the face. Discard or deposit in decontamination bin.
- Mask or N95 Respirator: The front of the mask is contaminated—do not touch it! Grasp the bottom strap first, lift over head, then grasp the top strap and lift off. Discard in waste receptacle.
- Hand Hygiene: Wash hands vigorously with soap and warm water for at least 20 seconds (mandatory if exposed to spores/blood) or apply alcohol-based hand rub until completely dry.
4. Earle Spaulding's Medical Device Classification Scheme
In 1968, Dr. Earle Spaulding devised a rational approach to medical device disinfection and sterilization based on the degree of tissue invasiveness and resultant risk of infection transmission.
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| SPAULDING CLASSIFICATION TAXONOMY |
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| [ CRITICAL ITEMS ] [ SEMI-CRITICAL ITEMS ] [ NON-CRITICAL ITEMS]|
| - Enters sterile tissue - Contacts mucous - Contacts intact |
| or vascular system membranes / non-intact skin only |
| - Examples: Scalpels, skin - Examples: ECG leads|
| cardiac catheters, - Examples: Endoscopes, NIBP cuffs, pumps, |
| laparoscopes, implants laryngoscope blades, TEE patient monitors |
| |
| LEVEL REQUIRED: LEVEL REQUIRED: LEVEL REQUIRED: |
| *** STERILIZATION *** *** HIGH-LEVEL (HLD) *** *** LOW / INTERM. ***|
| (Destroys all life, (Destroys all microbes (Destroys vegetative |
| including endospores) except high-count spores) bacteria & viruses) |
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Detailed Spaulding Matrix & Processing Methods
| Classification | Clinical Contact Definition | Representative Medical Devices | Required Germicidal Level | Validated Processing Technologies & Chemicals |
|---|---|---|---|---|
| Critical | Enters normally sterile human tissue, bone, or the vascular bloodstream | Surgical instruments, cardiac catheterization guide wires, rigid arthroscopes, laparoscopes, biopsy forceps, implantable pacemakers, IV infusion cannulas | STERILIZATION<br>(Complete destruction of all viable microorganisms, including large numbers of bacterial endospores) | - High-Pressure Saturated Steam: $121^\circ\text{C}$ for 30 min (gravity) or $132^\circ\text{C}/134^\circ\text{C}$ for 4 min (dynamic air removal / prevacuum).<br>- Ethylene Oxide (EtO) Gas: Low-temp ($37\text{--}55^\circ\text{C}$) for heat/moisture-sensitive electronics; requires aeration.<br>- Hydrogen Peroxide Gas Plasma (STERRAD): Low-temp radio-frequency plasma sterilization.<br>- Liquid Chemical Sterilants: Peracetic acid ($0.2%$) or glutaraldehyde ($>2.4%$) with extended soak ($3\text{--}10\text{ hours}$). |
| Semi-Critical | Contacts intact mucous membranes or non-intact skin; does not penetrate sterile tissue | Flexible gastrointestinal endoscopes, bronchoscopes, laryngoscope blades, respiratory therapy ventilator circuits, transesophageal echocardiography (TEE) probes, endocavitary ultrasound probes | HIGH-LEVEL DISINFECTION (HLD)<br>(Destruction of all vegetative bacteria, mycobacteria, viruses, and fungal spores; may not kill large numbers of bacterial spores) | - Glutaraldehyde ($\ge 2.0%$, e.g., Cidex): $20\text{--}45\text{ min}$ soak at $20\text{--}25^\circ\text{C}$. Requires chemical indicator strip testing for Minimum Effective Concentration (MEC).<br>- Ortho-phthalaldehyde (OPA $0.55%$, e.g., Cidex OPA): $12\text{ min}$ manual soak at $20^\circ\text{C}$ or $5\text{ min}$ in Automated Endoscope Reprocessor (AER) at $25^\circ\text{C}$.<br>- Accelerated Hydrogen Peroxide ($7.5%$).<br>- Peracetic Acid ($0.2%$).<br>Must be followed by thorough sterile/filtered water rinse. |
| Non-Critical | Contacts only intact skin; does not touch mucous membranes or internal tissue | Non-invasive blood pressure (NIBP) cuffs, ECG lead wires and patient trunk cables, pulse oximeter probes, infusion pump chassis, patient monitors, defibrillator paddles, hospital beds | LOW-LEVEL to INTERMEDIATE-LEVEL DISINFECTION<br>(Kills most vegetative bacteria, fungi, and enveloped viruses; intermediate also kills M. tuberculosis and non-enveloped viruses) | - Quaternary Ammonium Compounds (Quats): Low-level surface cleaning.<br>- $70%$ Isopropyl Alcohol (IPA): Fast-acting intermediate wipe for non-porous surfaces and optical windows.<br>- Sodium Hypochlorite (Bleach 1:10 dilution, $5,000\text{ ppm}$): Mandatory intermediate/sporicidal agent for C. diff environments.<br>- Accelerated Hydrogen Peroxide wipes: $1\text{--}3\text{ minute}$ contact time. |
5. Chemical Disinfectants, Minimum Effective Concentration (MEC) & Contact Times
For chemical disinfection to achieve its validated germicidal claim, technicians must strictly enforce two parameters: chemical potency and wet contact dwell time.
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| CHEMICAL DISINFECTION REQUISITES & MONITORING |
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| 1. MINIMUM EFFECTIVE CONCENTRATION (MEC) |
| - Chemical test strips must be dipped before EACH use batch |
| - Verifies active aldehyde/peroxide concentration has not diluted |
| - Must document date, time, strip expiration, and pass/fail result |
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| 2. WET CONTACT DWELL TIME |
| - The surface must remain actively wet with disinfectant for the |
| entire manufacturer-specified dwell period |
| - Standard Quat Wipes: 2 to 4 minutes |
| - Sporicidal Bleach Wipes: 3 to 5 minutes |
| - Rapid Hydrogen Peroxide Wipes: 1 to 2 minutes |
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Critical Safety Considerations for HLD Chemicals
- Glutaraldehyde (Cidex): Emits toxic vapors causing occupational asthma, contact dermatitis, and mucous membrane irritation. OSHA ceiling limit is $0.05\text{ ppm}$. Must be mixed and utilized under dedicated chemical fume hoods or ductless vapor extraction enclosures.
- Ortho-phthalaldehyde (OPA): Possesses much lower vapor pressure than glutaraldehyde, making it safer for respiratory exposure, but stains skin and protein residues gray/black. Contraindicated for reprocessing cystoscopes used in patients with a history of bladder cancer due to anaphylactoid hypersensitivity reactions.
- Rinsing Requirements: Devices subjected to HLD must undergo extensive rinsing with sterile or $0.2,\mu\text{m}$-filtered water (typically three separate rinses) to eliminate chemical residues that cause chemical colitis, mucosal sloughing, or tissue necrosis.
6. Biomedical Shop Decontamination & Field Servicing Protocols
Biomedical departments must maintain strict separation between contaminated and clean zones to prevent the HTM workshop from becoming an infection vector.
Shop Layout & Intake Workflow
- Designated Decontamination Area (Dirty Side):
- Negative airflow differential relative to adjacent shop corridors with dedicated exhaust to the exterior.
- Stainless steel wash basins, deep sinks, chemical eye wash stations, and biological biohazard waste containers.
- Incoming equipment must be received, inspected, and fully decontaminated on the dirty side prior to transfer to clean repair benches.
- Decontamination Protocol for Equipment Leaving Clinical Units:
- Equipment used in isolation rooms must be wiped down with hospital-approved disinfectant adhering to label dwell time before being removed from the clinical unit.
- If an internal pneumatic or mechanical assembly is suspected of biofluid contamination (e.g., suction pump fluid canister overflow into internal motor), the device must be sealed in a labeled biohazard transport bag for processing in the HTM decontamination suite.
- Servicing in Isolation Rooms:
- Take only essential diagnostic test analyzers and hand tools into isolation rooms.
- Encase test instruments (e.g., electrical safety analyzers, NIBP simulators) in clear protective plastic barriers or cleanable covers.
- Wipe all tools and cables with hospital-approved disinfectant upon exiting the isolation anteroom.
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Test Your Knowledge
According to the Spaulding medical device classification system, into which category does a flexible gastrointestinal endoscope fall, and what is the minimum level of germicidal processing required before reuse on another patient?
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Test Your Knowledge
A biomedical equipment technician is exiting an isolation room after servicing a telemetry transmitter on a patient under Contact Precautions. According to standard CDC guidelines, which PPE item must be removed FIRST during the doffing sequence?
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Test Your Knowledge
When decontaminating a patient monitor and infusion pump retrieved from an isolation room where the patient was diagnosed with Clostridioides difficile (C. diff), which disinfectant chemistry is required to destroy the bacterial endospores?
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Test Your Knowledge
A BMET is dispatched to replace a defective optical pulse oximeter module inside an Airborne Infection Isolation Room (AIIR) housing an active pulmonary tuberculosis patient. Which set of engineering controls and PPE is mandatory for this encounter?
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