CDRH CBER TSE INSTRUMENT DECONTAMINATION PROJECT

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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

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INSTRUMENTS

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

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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.

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WHO protocols

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

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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

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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

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1. Use of Containment Pans and Lids for
Autoclaving Caustic Solutions

• Stanley A. Brown, Katharine Merritt
• Am J. Infection Control
• 31 257-260, 2003.

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The problem

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

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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

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somepansandlids

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Lid (F) Pan (4), Nalgene Instrument pipet
sterilizing panfilled with 1 liter of NaOH
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note gutter drain slot
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lid contained inside pan lip
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Lid (D) Pan (2), NaOH in an open beaker in the
pan
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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

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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?

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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

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1 hr bleach vs- 5x autoclave in NaOHNeedle
holder carbide jaws
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1x bleach -vs- 5x autoclave in NaOHneedle holder
gold handles
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Germany vs- Pakistan 5x autoclave in NaOH
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Germany vs- Pakistan 5x soak in bleach
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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 its going to corrode, it will do it
  first try
• no need for long experiments

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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

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0.5 x 15 mm SS wire glued in Eppendorf tip
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pins over 96 well plate
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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)

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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 60C, 30 min Klenzyme, then DW
• 2. autoclave 1 hr in NaOH, then US clean
• 3. bleach 1 hr then US clean
• 4. uncleaned controls

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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)

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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

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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

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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

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SEM of microbes on uncleaned pin
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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

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