Introduction to Disinfection and Sterilization for Hook Reprocessing

Basic principles of disinfection and sterilization required for hook reprocessing.

Table of Contents

Introduction

Proper hook reprocessing is critical to prevent transmission of bloodborne pathogens and infection. The Denver Suspension Collective (DSC) Hook Reprocessing Protocol details the process but is not a suitable resource someone unfamiliar with the basic concepts of disinfection and sterilization. This guide is a preamble to those basic concepts, the equipment and supplies used, and compliance with regulatory standards.

Terminology and Basic Concepts

Key Terms

  • Cleaning: Physical removal of organic matter and contaminants from instruments using detergent, water, and mechanical action.
  • Disinfection: The process of eliminating most pathogenic microorganisms (except bacterial spores) on inanimate objects.
  • Sterilization: The complete elimination of all microorganisms including bacterial spores.
  • Cross-contamination: The transfer of harmful microorganisms from one surface, substance, or person to another.
  • Bioburden: The number of contaminating organisms on a material.
  • Biofilm: An accumulation of microorganisms and their extracellular products on a surface.

Hierarchy of Infection Control

  1. Cleaning: First and most essential step for all items
  2. Disinfection: Intermediate step in the reprocessing of critical items that will be sterilized (like hooks); may be the final step for non-critical items that don’t penetrate skin
  3. Sterilization: Final and required step for all critical items that penetrate skin (such as hooks)

Disinfection vs. Sterilization

Disinfection

  • Definition: Process that eliminates many or all pathogenic microorganisms on inanimate objects, except bacterial spores.
  • Applications: Used for surfaces, non-critical items, and some semi-critical items.
  • Levels:
    • Low-level disinfection: Kills most vegetative bacteria, some fungi, and some viruses (enveloped viruses)
    • Intermediate-level disinfection: Kills vegetative bacteria, most fungi, most viruses, and some bacterial spores
    • High-level disinfection: Kills all microorganisms except high numbers of bacterial spores
  • Limitations: Cannot ensure complete elimination of all microbial life, particularly resistant bacterial spores.

Sterilization

  • Definition: Process that destroys or eliminates all forms of microbial life, including bacterial spores.
  • Applications: Required for all critical items that enter sterile tissue or the vascular system.
  • Methods:
    • Steam under pressure (autoclaving) - Most common and preferred method for metal instruments
    • Ethylene oxide (EtO) gas - For heat-sensitive materials; common for pre-packaged sterile supplies like piercing needles and skin markers
    • Dry heat - For materials damaged by steam
    • Hydrogen peroxide plasma - For heat-sensitive materials
    • Chemical sterilants - Extended exposure to high-level disinfectants

Spaulding Classifications

The CDC’s Spaulding Classification System is the standard for determining appropriate reprocessing requirements in healthcare settings. This system categorizes medical devices based on their intended use and associated risk of infection transmission.

Classification Definition Examples Minimum Required Processing Rationale
Critical Items Items that enter sterile tissue or the vascular system Surgical instruments, implants, needles, hooks, catheters Sterilization These items present a high risk of infection if contaminated with microorganisms, especially bacterial spores
Semi-critical Items Items that contact mucous membranes or non-intact skin Respiratory therapy equipment, endoscopes, laryngoscope blades High-level disinfection (minimally)
Sterilization (preferably)		 These items contact mucous membranes which generally offer some barrier to infection
Non-critical Items Items that contact intact skin but not mucous membranes Blood pressure cuffs, stethoscopes, furniture, countertops Low to intermediate-level disinfection Intact skin acts as an effective barrier to most microorganisms

Why Hooks Must Be Sterilized, Not Just Disinfected

Any instrument that penetrates the skin or mucous membranes and contacts blood is a “critical item” that must be sterilized. This same principle applies to suspension hooks.

Disinfection alone is insufficient because:

  1. Disinfection cannot reliably eliminate bacterial spores, which can cause serious infections when introduced into the body
  2. Hooks breach the skin’s protective barrier and introduce direct access to the bloodstream
  3. Infectious doses of pathogens can be very small when introduced directly into blood or tissue
  4. Some bloodborne pathogens (like Hepatitis B virus) can survive on surfaces for extended periods and remain infectious

Disinfectants and Their Applications

Common Types of EPA-Registered Disinfectants Used in Body Art Settings

Disinfectant Type Mechanism Advantages Disadvantages EPA Toxicity Category
Accelerated Hydrogen Peroxide (AHP) Free radical oxidation of cell components Broad spectrum, environmentally friendly, rapid action Can be corrosive to some metals at high concentrations Category 4
Quaternary Ammonium Compounds (Quats) Disruption of cell membranes Good cleaning properties, stable, non-corrosive Limited effectiveness against certain pathogens Category 2 and 3
Phenolics Disruption of cell walls Broad spectrum, residual activity Potential toxicity, environmental concerns Category 1

EPA’s List S: Antimicrobial Products Effective Against Bloodborne Pathogens

Disinfectant labeling such as “commercial grade” or “hospital grade” can be misleading and should not be relied upon when choosing a suitable product. The Environmental Protection Agency (EPA) maintains a list of registered antimicrobial products that are effective against bloodborne pathogens, specifically HIV, Hepatitis B, and Hepatitis C. This is known as “List S” and is particularly relevant for body art settings. The complete, up-to-date list can be found at EPA’s Registered Antimicrobial Products Effective Against Bloodborne Pathogens

Appropriate Selection and Use

When selecting a disinfectant, consider:

  • Efficacy: Level of antimicrobial activity required (products on EPA List S for bloodborne pathogens)
  • Material compatibility: Will it damage the surface or instrument?
  • Safety: Toxicity and irritation potential
  • Ease of use: Contact time, preparation required
  • Environmental impact: Disposal considerations

Role of Disinfectants in Hook Processing

In hook reprocessing, disinfectants are primarily used for:

  1. Pre-cleaning: Removing gross contamination before thorough cleaning
  2. Surface decontamination: Cleaning work surfaces and non-critical items
  3. Environmental cleaning: Maintaining general cleanliness of the area

Ultrasonic Cleaners and Enzymatic Solutions

Ultrasonic Cleaner Function

Ultrasonic cleaners use high-frequency sound waves (typically 35-160 kHz) to create cavitation bubbles in a liquid cleaning solution. When these bubbles collapse, they:

  1. Create microscopic “scrubbing” action
  2. Reach crevices and areas inaccessible to manual cleaning
  3. Dislodge contaminants from instrument surfaces

Components of an Ultrasonic Cleaner

  1. Tank: Typically stainless steel, holds cleaning solution
  2. Transducers: Convert electrical energy to sound waves
  3. Generator: Produces high-frequency electrical energy
  4. Heater: Maintains optimal solution temperature
  5. Timer: Controls cleaning cycle duration
  6. Cover: Reduces noise and evaporation

Enzymatic Detergents

Enzymatic detergents contain specific enzymes that break down biological materials:

  1. Proteases: Break down proteins (including blood)
  2. Lipases: Break down fats and oils
  3. Amylases: Break down starches
  4. Carbohydrases: Break down carbohydrates

Benefits of enzymatic cleaners:

  • Target specific biological contaminants
  • Work at near-neutral pH (less corrosive)
  • Environmentally friendlier than harsh chemicals
  • More effective than regular detergents for biological materials

Selecting Appropriate Enzymatic Detergents

While formal standards exist (AAMI TIR30, ISO 17664), most enzymatic detergents don’t explicitly reference these on their labeling unlike disinfectants. Instead, look for:

  1. Intended Use Statement: Must explicitly state it’s for removing blood and other biological materials from medical/surgical instruments
  2. Material Compatibility: Technical documentation should state it’s compatible with the materials you use (e.g. stainless steel, titanium)
  3. Equipment Compatibility: Ensure compatibility with ultrasonic cleaners (low-foaming properties)
  4. Enzyme Formulation: Multi-enzymatic formula
  5. Manufacturer Reputation: Established company with healthcare focus and technical specification availability

Common enzymatic detergents used in body art settings include Alconox Tergazyme, Metrex EmPower, and UPS all-in-ONE.

Optimal Use of Ultrasonic Cleaners

  1. Preparation:
    • Use fresh cleaning solution at the start of each day
    • Mix according to manufacturer’s instructions
    • Degas solution before first use (run empty for 5 minutes)
    • Maintain proper temperature - temperatures above 40°C (104°F) can cause the hardening of proteins
  2. Pre-cleaning:
    • Rinse instruments to remove gross contamination
    • Disassemble instruments if possible
    • Keep sharps separate to prevent damage
  3. Loading:
    • Do not overload the basket
    • Ensure instruments are fully submerged
    • Arrange to maximize surface exposure
    • Use instrument cassettes or holders when available
  4. Cycle Time:
    • Typically 5-10 minutes for properly pre-cleaned instruments
    • Follow manufacturer recommendations
    • Extended time may be needed for heavily soiled items
  5. Post-ultrasonic Cleaning:
    • Rinse instruments thoroughly with clean water
    • Visually inspect for cleanliness
    • Dry before packaging for sterilization

What Ultrasonic Cleaning Does and Doesn’t Do

Does Does Not
Removes debris from hard-to-reach areas Sterilize instruments
Enhances manual cleaning efficacy Disinfect instruments
Standardizes the cleaning process Replace manual pre-cleaning for heavily soiled items
Reduces handling of contaminated instruments Remove all contaminants without proper solution and time
Improves efficiency of the cleaning process

Testing Ultrasonic Cleaner Efficiency

  1. Aluminum Foil Test:
    • Place a sheet of aluminum foil in the cleaner
    • Run for 3 minutes
    • Examine for uniform pattern of indentations
    • Absence of pitting indicates weak spots
  2. Commercial Test Strips:
    • Specially designed to change color when exposed to cavitation
    • Place in different areas of the tank
    • Run a normal cycle
    • Evaluate color change pattern

Steam Autoclaves: Function and Operation

Basic Principles

A steam autoclave uses saturated steam under pressure to achieve sterilization. The three critical parameters for steam sterilization are:

  • Temperature
  • Pressure
  • Time

How Steam Sterilization Works

  1. Steam Generation: Water is heated to create steam
  2. Air Removal: Air is evacuated from the chamber (air impedes heat transfer)
  3. Steam Penetration: Steam enters the chamber and penetrates materials
  4. Heat Transfer: Steam condenses on cooler surfaces, releasing latent heat
  5. Microbial Destruction: Heat denatures proteins and destroys microorganisms
  6. Drying: Excess moisture is removed

Types of Steam Autoclaves

The EN 13060 standard classifies autoclaves into three categories based on their capabilities:

  1. Class N (Non-vacuum) Autoclaves
    • Uses gravity displacement for air removal
    • Suitable only for solid, unwrapped instruments
    • Cannot effectively sterilize hollow instruments or porous loads
    • Not suitable for wrapped instruments or those with lumens
    • Lowest cost option but most limited capabilities
    • Common examples: Midmark M9, older Tuttnauer ValueKlave models, some basic tabletop models
  2. Class B (Big Small Sterilizers) Autoclaves
    • Uses fractioned pre-vacuum for air removal (multiple vacuum pulses)
    • Suitable for all types of loads: solid, hollow, porous, wrapped and unwrapped
    • Can sterilize complex instruments with lumens and cavities
    • Required for wrapped instruments and implantable devices
    • Highest performance but more expensive
    • Common examples: Tuttnauer Elara 11, W&H Lisa, SciCan BRAVO, Midmark M11
  3. Class S (Specified) Autoclaves
    • Uses specialized air removal techniques (often single vacuum pulse)
    • Intermediate capability between Class N and Class B
    • Designed for specific products as specified by manufacturer
    • Limitations must be clearly specified by manufacturer
    • Suitable for some hollow instruments depending on specifications
    • Common examples: SciCan STATIM 2000/5000 (cassette autoclaves), some Tuttnauer EZ models

Critical Parameters

  1. Temperature:
    • 121°C (250°F) for 30 minutes at 15 PSI, OR
    • 134°C (273°F) for 15 minutes at 30 PSI
  2. Time:
    • Begins only after the chamber reaches sterilization temperature
    • Must be adjusted based on load size and type
    • Cooling and drying time is additional
  3. Pressure:
    • Directly related to temperature in saturated steam
    • Measured in PSI (pounds per square inch) or kPa
    • Common pressure: 15-30 PSI

Autoclave Operation Procedure

  1. Pre-sterilization Checks:
    • Check water reservoir level
    • Ensure drain screen is clean
    • Verify chamber is clean
  2. Loading:
    • Use appropriate packaging materials
    • Leave space between packages
    • Orient items to allow steam penetration
    • Do not overload
  3. Cycle Selection:
    • Choose appropriate cycle based on items being sterilized
    • Packaged instruments vs. unwrapped items
    • Porous vs. non-porous loads
  4. Monitoring:
    • Use appropriate chemical indicators
    • Include a Type 5 integrator in each load
    • Verify and document cycle parameters (time, temperature, and pressure reached)
  5. Post-sterilization:
    • Allow proper cooling time
    • Check indicators for appropriate color change
    • Verify packages are dry
    • Record results in sterilization log

Factors Affecting Steam Sterilization

  1. Air Pockets: Prevent steam contact with surfaces
  2. Improper Packaging: Can block steam penetration
  3. Overloading: Prevents proper steam circulation
  4. Inadequate Cleaning: Organic matter protects microorganisms
  5. Improper Arrangement: Items must be positioned to allow steam contact
  6. Chamber Temperature: Must reach and maintain sterilization temperature
  7. Altitude: Requires adjustment of time/pressure parameters

Chemical Sterilization Indicators/Integrators

Sterilization indicators monitor the sterilization process and help ensure that sterilization conditions have been met. Chemical indicators provide immediate visual confirmation that sterilization parameters were exposed to specific conditions, while biological indicators verify actual sterilization effectiveness by demonstrating the killing of highly resistant bacterial spores. The ISO 11140-1:2014, which is the standard for chemical indicators in health care products, classifies them into different types:

Type Function Example Use Limitations/Advantages When to Use
Type 1: Process Indicators / External indicators Change color when exposed to one or more sterilization parameters Autoclave tape Applied to the outside of packages to distinguish processed from unprocessed items Only indicates that the package was exposed to a sterilization process, not that sterilization was achieved On every package as a visual cue for processing status
Type 2: Specific Test Indicators Designed for specific testing procedures Bowie-Dick test for steam sterilizers Tests for air removal and steam penetration in pre-vacuum sterilizers Specific to testing equipment function rather than monitoring routine loads Daily before first processed load
Type 3: Single-Parameter Indicators Reacts to one critical parameter of sterilization Temperature-sensitive indicators Internal monitoring of a specific critical parameter Does not confirm that all sterilization parameters were met When monitoring a specific parameter is sufficient for the item being sterilized
Type 4: Multi-Parameter Indicators Reacts to two or more critical parameters Indicators that respond to both time and temperature Internal monitoring within each package More reliable than Type 1 or 3 indicators For routine internal package monitoring where higher reliability is desired
Type 5: Integrating Indicators Reacts to all critical parameters of sterilization Integrating indicators that respond to time, temperature, and presence of steam Placed inside packages near the center or area most difficult to sterilize Performance comparable to biological indicators in some cases In every sterilization load according to Denver regulations
Type 6: Emulating Indicators Reacts to all critical parameters with very precise tolerances Cycle-specific indicators designed for specific time/temperature criteria When extra precision is needed Most precise chemical indicator available For critical loads where precise parameter verification is essential

Biological (Spore) Testing

What is Biological Monitoring?

Biological monitoring uses bacterial spores to verify sterilization efficacy. These spores are chosen for their extreme resistance to the sterilization method being tested. For steam sterilization, Geobacillus stearothermophilus spores are used. Denver regulations require monthly testing using a commercial biological monitoring system.

Types of Biological Indicators (BIs)

  1. Self-contained BIs:
    • Contain both the spores and growth medium in a single vial
    • Medium is released after sterilization
    • Results available after incubation (typically 24-48 hours)
    • Easy to use with minimal risk of contamination
  2. Spore Strips:
    • Paper strips impregnated with spores
    • Must be transferred to growth medium after sterilization
    • Requires more handling and has higher contamination risk
    • Less expensive but more labor-intensive
  3. Rapid Readout BIs:
    • Detect enzymes associated with spore metabolism
    • Results available in 1-3 hours
    • More expensive but allows faster release of loads
    • Increasingly common in high-volume settings

Proper Biological Testing Protocol

  1. Frequency:
    • Monthly at minimum (per Denver regulations)
    • After sterilizer repairs or malfunction
    • After relocation of sterilizer
    • For validation of new sterilization processes
  2. Placement:
    • Inside a standard pack or PCD (Process Challenge Device)
    • In the area most challenging for sterilization (typically center/bottom of the load)
  3. Control Testing:
    • Always run a control BI from the same lot
    • Do NOT sterilize the control
    • Incubate alongside the test BI
    • Control must show growth for valid test
  4. Processing:
    • Label test and control BIs appropriately
    • Process test BI through normal sterilization cycle
    • Activate and incubate both test and control according to manufacturer instructions
    • Maintain proper incubation temperature
  5. Interpretation:
    • Negative result (no growth in test BI, growth in control): Sterilization successful
    • Positive result (growth in test BI, growth in control): Sterilization failure
    • Invalid test (no growth in control): Test must be repeated

Responding to Failed Biological Tests

  1. Immediate Actions:
    • Remove sterilizer from service
    • Recall all items processed since last negative BI
    • Re-sterilize recalled items in a different sterilizer
  2. Troubleshooting:
    • Check sterilizer operating parameters
    • Inspect door gaskets and seals
    • Verify proper loading procedures
    • Review maintenance records
  3. Repeat Testing:
    • Run three consecutive empty cycles with BIs
    • All must test negative before returning to service
    • Document all test results and corrective actions
  4. External Testing:
    • If problems persist, arrange for service technician
    • Consider independent laboratory testing
    • Follow manufacturer recommendations

Quality Control and Documentation

Required Documentation

According to Denver regulations, maintain the following records for a minimum of two years:

  1. Sterilization Logs:
    • Date and time of each load
    • Contents of load
    • Exposure time and temperature
    • Pressure readings
    • Operator identification
    • Results of chemical indicators
    • Corrective actions (if needed)
  2. Biological Monitoring Records:
    • Test date
    • Test results
    • Control results
    • Laboratory reports
    • Corrective actions taken for failed tests
  3. Maintenance Records:
    • Service dates
    • Repairs performed
    • Validation testing after repairs
    • Preventive maintenance schedule

Resources and References