Presentation on theme: "CDRH - CBER TSE INSTRUMENT DECONTAMINATION PROJECT Stanley Brown, Katharine Merritt, Terry Woods, Scott McNamee and Deanna Busick CDRH/ OST / DMMS & DLS."— Presentation transcript:
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 protocols 1.autoclave in 1 N NaOH, 121°C, 30 min 2.immerse 1 hr in: 2a. 1 N NaOH, or 2b. sodium hypochlorite (20,000 ppm Cl) --- then autoclave in water 121°C, 1 hr 3.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.
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
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
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
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
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