Sterilization and disinfection

Background

• The process of sterilization destroys all forms of microbial life
• May be physical or chemical methods
  • Steam under pressure
  • Dry heat
  • EtO gas
  • Hydrogen peroxide gas plasma
  • Liquid chemicals
• Equipment must be cleaned first, before attempting to disinfect or sterilize it

Spaulding Classification of Medical Equipment

Classification	Contact with	Processing	Examples
Critical	Sterile tissue or vascular system	Cleaning followed by sterilization	Surgical instruments, biopsy instruments, and foot care equipment
Semi-critical	Non-intact skin or mucous memranes, but not penetrating the skin	Cleaning followed by a minimum high level disinfection	Respiratory equipment, flexible endoscopes
Non-critical	Intact skin	Cleaning followed by low level disinfection	Trourniquets, BP cuffs, linen, and furtniture

Rutala Modification

• Endoscopes, which secondarily enter sterile tissues, should be considered critical

Medical Device Reprocessing Department (MDRD)

• Needs separate areas for receiving soiled instruments, decontaminating, cleaning, sterilizing, and storing
• Treated essentially like an OR, with controlled temperature and humidity, with dedicated ventilation system
• Negative pressure in decontamination areas and positive pressure in clean areas

Pre-Cleaning

• Dismantle and sort devices, then soak them

Cleaning

• Remove all visible soil from every accessible surface
• Can use ultrasonic machines and washing machines
• Rinse to remove detergents, then dry

Sterilization

• High temperature sterilization whenever possible
• Low-temperature sterilization can be done for heat sensitive critical and semi-critical items
  • Uses gas, including hydrogen peroxide gas plasma or vapour, or ozone (but that needs 4 hours)
  • Needed for things with plastic, for example
• Liquid emersion can be done for heat sensitive crticical and semi-critical items
  • Hydrogen peroxide most common liquid

Monitoring

• Spore tests: compare a strip that went through the autoclav to a control that was held outside
• ATP system test strips

Storage

• Equipment must be stored until results are available from the spore test for that batch
• Controlled temperature and humidity

Further Reading

• APIC