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Decontamination of Surfaces Contaminated with Prions

Decontamination of Surfaces Contaminated with Prions. Dr. Gerald McDonnell. Iatrogenic prion transmission. Human tissues and contaminated surfaces can transmit TSEs Human tissue examples Medical device examples Experimental evidence Zobeley et al , 2001

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Decontamination of Surfaces Contaminated with Prions

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  1. Decontamination of Surfaces Contaminated with Prions Dr. Gerald McDonnell

  2. Iatrogenic prion transmission • Human tissues and contaminated surfaces can transmit TSEs • Human tissue examples • Medical device examples • Experimental evidence • Zobeley et al, 2001 • ‘Prions are readily and tightly bound to stainless steel surfaces and can transmit scrapie to recipient mice after short implant exposure times’

  3. Intrinsic Resistance • Prions demonstrate resistance to routine methods of decontamination and sterilization • Prions are proteins, not microorganisms

  4. Current Decontamination Methods • Cleaning • Can cleaners increase or decrease the risk? • Physical removal • Lipophilic soil • Environmental fate • Which cleaners should/should not be recommended? • Aldehyde-based cleaners should be contra-indicated • Use of alkaline cleaners

  5. Current Decontamination Methods • Steam sterilization • Data in the literature conflicting • ‘Steam sterilization alone is NOT effective’ • Higher sterilization temperatures may be less effective • Published reports of survival following gravity displacement autoclaving • Ernst & Race(1993): 132C/ 1 hour • Taylor (2000): 134C/ 1 hour

  6. Current Decontamination Methods • Sodium hydroxide • Device damage concerns • Autoclave damage • Safety concerns Reprinted on request from Hotel Dieu Grace, Windsor, Ontario

  7. Summary • TSE’s can be transferred via medical devices and other surfaces • Current recommended decontamination methods need to be verified and validated • Priocidal, compatibility, safety • Alternative decontamination technologies? • High and low temperature

  8. Decontamination Research • Test Methodology • Method Development • Method Validation • Decontamination Methodology • Existing recommended methods • Developing technologies

  9. In Vivo Methodology

  10. In Vivo Methodology • Study design • TSE Strain: Scrapie 263K • Test animal: Syrian hamsters • Test device: stainless steel wires • Test inoculum • 10% brain homogenate, 1 hour • Dried 16 hours, room temperature • 14 control groups (12 animals) • Positive controls (LD50), diluted in ‘negative’ brain homogenate • Negative controls • Wash-off controls • Decontamination methods (12 animals/group)

  11. Positive Controls

  12. Wash-Off Controls *At 280 days incubation (>9 months)

  13. Autoclave studies

  14. Cleaning Studies *Formulated for efficacy and compatibility on medical devices and other surfaces

  15. Further Technologies *Previously published as effective in suspension studies

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