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

INSTRUMENTS

• Surgical – primarily reusable.

but also “Single” Use Devices, SUDs

exposed to contaminated human tissues

• tissue processing

exposed to animal tissues

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.

WHO protocols1. autoclave in 1 N NaOH, 121°C, 30 min2. immerse 1 hr in: 2a. 1 N NaOH, or 2b. sodium hypochlorite (20,000 ppm Cl) --- then autoclave in water 121°C, 1 hr3. soak in NaOH or Bleach, rinse then steam autoclave, 1 hr

*** all followed by routine (ultrasonic) cleaning, rinsing, and sterilization

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

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

1. Use of Containment Pans and Lids for Autoclaving

Caustic Solutions

Stanley A. Brown, Katharine Merritt

Am J. Infection Control

31: 257-260, 2003.

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.

MethodsA. 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

somepansandlids

Lid (F) Pan (4), Nalgene Instrument pipet sterilizing pan

filled with 1 liter of NaOH

note gutter drain slot

lid contained inside pan lip

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

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

2. The Effects on the instruments of the WHO protocols

for TSE decontamination

manuscript in preparation

Questions:

1. Will protocols cause corrosion?

2. Are certain instruments more at risk?

3. Does corrosion affect function?

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

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

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

Germany –vs- Pakistan 5x autoclave in NaOH

Germany –vs- Pakistan 5x soak in bleach

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

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

0.5 x 15 mm SS wire glued in Eppendorf tip

pins over 96 well plate

4. CDRH PIN STUDY THREE QUESTIONS TO BE ANSWERED

1. 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)

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

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)

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

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

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

SEM of microbes on uncleaned pin

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

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