Validating Sterilization of Medical Devices

1. Validating Sterilization of Medical Devices CDR Martha O’Lone, RN, BSN Infection Control Devices Branch DAGID / ODE / FDA

2. Objectives • Provide background information on sterilization validation for medical devices • Obtain panel guidance on how to design and interpret sterilization validation studies for medical devices after exposure to TSE material

3. Questions • For prion contaminated critical medical devices: • What is the acceptable sterilization process for prion removal/ inactivation? • What endpoint is appropriate? • Log reduction of infectivity? • Is there an indicator agent for prions?

4. Validating Sterilization of Medical Devices • Spaulding Classification of Medical Devices • Sterilization Methods • Medical Device Reprocessing Steps • Healthcare Sterilization Processes • Medical Device Reprocessing Review • Validation • Available Recommendations/Guidelines

5. Spaulding Classification of Medical Devices BASED ON RISK OF INFECTION Critical devices Enter normally sterile body tissue: e.g., surgical instruments -Sterilization Semi- critical devices Contact mucous membranes: e.g., flexible endoscopes -Sterilization, if not feasible- Minimally high level disinfection Non- critical devices Contact intact skin: e.g., stethoscopes, electrocardiogram electrodes -Intermediate or Low level disinfection - Block, 5th edition

6. Descending Order of Resistance ???? Prions ???? • Bacterial Spores • Mycobacteria • Non-lipid or Small Viruses • Fungi • Vegetative Bacteria • Lipid or Medium-Size Viruses

7. Steps for Medical Device Reprocessing Cleaning Required for effective disinfection or sterilization Goal: Reduce bioburden Remove organic / inorganic clinical contaminants High Level Disinfection-semi critical devices Endpoint- To kill mycobacteria and some spores Sterilization- critical devices Validated process used to render a product free of all forms of viable microorganisms (AAMI) Endpoint- To kill spores (as an indicator microorganism)

8. Sterilization Processes Currently Used in Healthcare Settings • Steam (Moist Heat) Sterilization • Gravity displacement cycles - 121ºC, 20-30 min • Prevacuum cycles – 132-134 ºC, 3-5 min • Dry Heat Sterilization • Ethylene Oxide (EtO) Sterilization • Liquid Chemical Sterilization • Gas Plasma Hydrogen Peroxide Sterilization Process

9. Review of Reusable Medical Device Reprocessing • FDA Guidance: Labeling Reusable Medical Devices for Reprocessing In Health Care Facilities: FDA Reviewer Guidance, April, 1996 • Labeling for a reusable device that contacts the patient in some manner must include reprocessing instructions • The instructions must indicate the appropriate microbicidal process for the device • Critical - Sterilization • Semicritical – At least high level disinfection • Noncritical – Intermediate or low level disinfection • The reprocessing process must be feasible considering the intended location of reprocessing (e.g., health care facility or home use) • Reprocessing instructions must be validated

10. Sterilization Validation • Sterilization of critical medical devices • Objective: sterilization process should demonstrate a spore (BI) kill to achieve a sterility assurance level (SAL) of 1x10-6 • Standards/Guidance available to provide validation methods for traditional sterilization processes utilizing bacterial spores

11. Sterilization Validation • For prion contaminated critical medical devices: • What is the acceptable sterilization process for prion removal/ inactivation? • What endpoint is appropriate? • Log reduction of infectivity? • Is there an indicator agent for prions?

12. Virus Validation • For medical devices incorporating animal derived tissue • Objective: final product below one infectious particle per 106 devices • Similar to SAL 1 X 10-6 in traditional medical devices sterilization processes

13. Virus Validation Studies • Scaled down (e.g.1/100) manufacturing procedures • Relevant model viruses (DNA, RNA, single and double stranded enveloped and non-enveloped) • Spike virus in different steps in the manufacturing process and determine post-step PFU • Sum the viral clearance values for each manufacturing step

14. WHO Recommendations Annex III(For reprocessing CJD contaminated instruments) • Disposable Instruments: Incinerate (and all instruments exposed to high infectivity tissues.) • Heat Resistant Instruments: • Immerse in 1N NaOH • Heat in a gravity displacement autoclave at 121°C for 30 min, or 132º C for 3-5 min • Rinse in water • Routine sterilizationprocess

15. Draft CDC HICPAC Guidelines for CJD Decontamination • Critical or Semicritical Devices Exposed to High Risk Tissues and/or High Risk patients Keep instruments wet or damp until they are decontaminated Options: 1. Clean and sterilize the contaminated devices by immersion in 1N NaOH, remove, rinse in water and autoclave (sterilizer) in an open pan as recommended by WHO at 121° C or 134°C depending on type of sterilizer- gravity displacement or prevac- for 1hr 2. OR immerse instruments in 1N NaOH for 1 hour and heat in a gravity displacement sterilizer at 121°C for 30 minutes, clean; and subject to routine sterilization 3. Clean thoroughly, then autoclave at 134°C for 18 minutes in a prevacuum sterilizer or 132°C for 1 hour in a gravity displacement sterilizer. Discard contaminated medical devices that are impossible or difficult to clean