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CDRH - CBER TSE INSTRUMENT DECONTAMINATION PROJECT

CDRH - CBER TSE INSTRUMENT DECONTAMINATION PROJECT. Stanley Brown, Katharine Merritt, Terry Woods, Scott McNamee and Deanna Busick CDRH/ OST / DMMS & DLS David Asher, Kitty Pomeroy, Rolf Taffs CBER / OBRR / DETTD with funding from FDA, Office of Science & Health Coordination

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CDRH - CBER TSE INSTRUMENT DECONTAMINATION PROJECT

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  1. CDRH - CBER TSE INSTRUMENT DECONTAMINATION PROJECT Stanley Brown, Katharine Merritt, Terry Woods, Scott McNamee and Deanna Busick CDRH/ OST / DMMS & DLS David Asher, Kitty Pomeroy, Rolf Taffs CBER / OBRR / DETTD with funding from FDA, Office of Science & Health Coordination TSEAC 17 July 03

  2. INSTRUMENTS • Surgical – primarily reusable. but also “Single” Use Devices, SUDs exposed to contaminated human tissues • tissue processing exposed to animal tissues

  3. Disclaimer • The methods used were selected by the research teams, as reasonably inexpensive approaches, within the constraints of the FDA lab facilities and manpower, to: 1. provide an understanding of the issues 2. examine the feasibility of decontamination protocols recommended by WHO • These presentations do not constitute regulatory endorsement as methods to validate decontamination protocols.

  4. WHO protocols • autoclave in 1 N NaOH, 121°C, 30 min • immerse 1 hr in: 2a. 1 N NaOH, or 2b. sodium hypochlorite (20,000 ppm Cl) --- then autoclave in water 121°C, 1 hr • soak in NaOH or Bleach, rinse then steam autoclave, 1 hr *** all followed by routine (ultrasonic) cleaning, rinsing, and sterilization

  5. CDC website notes & warnings 1. autoclaving in NaOH can wreck autoclave and operators 2b. soaking in bleach can wreck instruments • these are based on CDRH studies

  6. CDRH / OST TSE Decontamination Research Issues based on WHO recommendations 1. safety of autoclaving in NaOH 2. effects of protocols 1 & 2 on instruments 3. develop pins as model “instruments” 4. Protein & Microbial decontamination

  7. 1. Use of Containment Pans and Lids for Autoclaving Caustic Solutions Stanley A. Brown, Katharine Merritt Am J. Infection Control 31: 257-260, 2003.

  8. The problem • WHO method #1: • place instruments in 1 N NaOH and autoclave at 121°C. • Some autoclave manufacturers have said: “do that and you have no warranty” • Note: must use gravity displacement autoclaves, with liquid (no vacuum) cycles.

  9. Methods A. 1 L of NaOH in a pan & cover B. 10 ml NaOH in beaker in a pan & cover 1. Place in table top gravity displacement autoclave 2. repeat 1 hr sterilization cycles 3. measure pH inside and out of pan & lid 4. measure pH of autoclave 6 liter water reservoir

  10. somepansandlids

  11. Lid (F) Pan (4), Nalgene Instrument pipet sterilizing panfilled with 1 liter of NaOH

  12. note gutter drain slot

  13. lid contained inside pan lip

  14. Lid (D) Pan (2), NaOH in an open beaker in the pan

  15. Results – autoclaving in NaOH • No pH changes outside the containment • Condensate inside container was caustic • No pH change in water reservoir • Conclusion: Autoclaving in NaOH can be done without damage to autoclave interior • Caution: handle hot caustic with care • Note: can not be done in Central Services • Note: may require larger (approved) pans

  16. The Effects on the instruments of the WHO protocols for TSE decontamination manuscript in preparation Questions: 1. Will protocols cause corrosion? Are certain instruments more at risk? Does corrosion affect function?

  17. Methods • Bought a bunch of instruments “surgical” from Roboz “Lab” from V W R some “Germany” some “Pakistan” • Repeated 1 hr cycles: autoclave in 1 N (3.9%) NaOH soak in 1 N (3.9%) NaOH soak in 6% NaOCl (28,500 ppm Cl) autoclave in water

  18. 1 hr bleach –vs- 5x autoclave in NaOHNeedle holder carbide jaws

  19. 1x bleach -vs- 5x autoclave in NaOHneedle holder gold handles

  20. Germany –vs- Pakistan 5x autoclave in NaOH

  21. Germany –vs- Pakistan 5x soak in bleach

  22. Results – Instrument Corrosion • Autoclaving in NaOH – darkening in some box joints titanium gets very dark • soaking in NaOH – no changes • soaking in NaOCl bleach – “good” instruments do OK exception: gold handles, carbide jaws “not so good” corrode, esp. welds & finger rings BUT: if it’s going to corrode, it will do it first try; no need for long experiments

  23. 3. Pins for “instruments” Needed a model “instrument” 1. like 25g needle & 1/2 cc syringe used in CBER hamster model 2. suspend over 96 well plates for serial dilutions of: bacteria, viruses, brain homogenate 3. autoclavable

  24. 0.5 x 15 mm SS wire glued in Eppendorf tip

  25. pins over 96 well plate

  26. 4. CDRH PIN STUDY THREE QUESTIONS TO BE ANSWERED • Will blood and tissue adhere to the pins? 2. Will the WHO cleaning protocols remove the blood and tissue? 3. Does damage to the instruments affect blood and tissue adherence and cleaning? (Stainless steel vs piano wire)

  27. blood and tissue adherence • Pins placed in a rack and immersed in slab of liver for 1 hr, left to dry for 24 hrs • Pins in rack and into 96 well plate with sheep blood 1 hr, left to dry for 24 hours 1. US clean: 60°C, 30 min Klenzyme, then DW 2. autoclave: 1 hr in NaOH, then US clean 3. bleach 1 hr: then US clean 4. uncleaned controls

  28. Results – blood and tissue • Uncleaned controls: More protein adhered to the pins from liver than from blood • Damaged pins not more adherent • Repeat exposure and US cleaning (5 times) did not result in increase of protein adherence • All cleaning protocols removed the protein as detected by Bradfords (less than 1 ul of blood)

  29. Bacterial Adherence • Pins placed in a suspension of (S. epidermidis) incubated for 24 hours then left to dry • Then U.S. cleaning or WHO • Then they were inserted into agar in a test tube and incubated for 24 hours

  30. Results - Bacterial Adherence (1) • autoclaving and bleach killed them all • tried “modified” WHO protocols: Dropped autoclave in 1N NaOH All US cleaning done at room temperature

  31. Bacteria Results (2)with modified WHO Approach • Only the pins treated with bleach showed no growth ??? killed or cleaned?? • The other procedures had fewer bacteria than the untreated control, but bacteria were present

  32. SEM of microbes on uncleaned pin

  33. CDRH Studies’ Conclusions • Some WHO protocols can damage some surgical instruments • The discoloration from NaOH does not seem to impair function or cleaning • Question: if bacteria were removed in the cleaning protocols? The final sterilization procedure would kill them. • Question: can prions be removed – CBER

  34. Now turn the podium over to Dr. David Asher from CBER

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