1. CJD: Recommendations for Disinfection and Sterilization in Health Care
William A. Rutala, Ph.D., M.P.H.
University of North Carolina (UNC) Hospitals and UNC School of Medicine

2. CJD: Disinfection and Sterilization Topics
Rationale for US recommendations
Epidemiological studies of prion transmission
Infectivity of human tissues
Efficacy of removing microbes by cleaning
Prion inactivation studies
Recommendations to prevent cross-transmission from medical devices contaminated with prions
Methodology-how methodology affects results

3. CJD: DISINFECTION AND STERILIZATION
Rationale for US recommendations
Epidemiological studies of prion transmission
Epidemiological studies of prion transmission via surgical instruments
Infectivity of human tissues
Efficacy of removing microbes by cleaning
Prion inactivation studies
Risk associated with instruments

4. Transmissibility of Prions
Transmission
Not spread by contact (direct, indirect, droplet) or airborne
Not spread by the environment
Experimentally-all TSEs are transmissible to animals, including the inherited forms
Epidemiology of CJD: sporadic-85%; familial-15%; iatrogenic-1% (primarily transplant of high risk tissues, ~250 cases worldwide)

5. Iatrogenic Transmission of CJD
Contaminated medical instruments
Electrodes in brain (2)
Neurosurgical instruments in brain (4)
Dura mater grafts (>110)
Corneal grafts (3)
Human growth hormone and gonadotropin (>130)

6. CJD: DISINFECTION AND STERILIZATION
Rationale for US recommendations
Epidemiological studies of prion transmission
Epidemiological studies of prion transmission via surgical instruments
Infectivity of human tissues
Efficacy of removing microbes by cleaning
Prion inactivation studies
Risk associated with instruments

7. CJD and Medical Devices
Six cases of CJD associated with medical devices
2 confirmed cases-depth electrodes; reprocessed by benzene, alcohol and formaldehyde vapor
4 cases-CJD following brain surgery, index CJD identified-1, suspect neurosurgical instruments
Cases occurred before 1980 in Europe
No known cases since 1980 and no known failure of steam sterilization

8. CJD: DISINFECTION AND STERILIZATION
Rationale for US recommendations
Epidemiological studies of prion transmission
Epidemiological studies of prion transmission via surgical instruments
Infectivity of human tissues
Efficacy of removing microbes by cleaning
Prion inactivation studies
Risk associated with instruments

9. Risk of CJD Transmission
Epidemiologic evidence (eye, brain) linking specific body tissue or fluids to CJD transmission
Experimental evidence in animals demonstrating that body tissues or fluids transmit CJD
Infectivity assays a function of the relative concentration of CJD tissue or fluid

10. Risk of CJD Transmission
Risk of Infection
Tissue
High
Brain (including dura mater), spinal cord, and eye
Low
CSF, liver, lymph node, kidney, lung, spleen, placenta, olfactory epithelium No
Peripheral nerve, intestine, bone marrow, whole blood, leukocytes, serum, thyroid gland, adrenal gland, heart, skeletal muscle, adipose tissue, gingiva, prostate, testis, tears, nasal mucus, saliva, sputum, urine, feces, semen, vaginal secretions, and milk
High-transmission to inoc animals >50%; Low-transmission to inoc animals >10-20% but no epid evidence of human inf

11. CJD: DISINFECTION AND STERILIZATION
Rationale for US recommendations
Epidemiological studies of prion transmission
Epidemiological studies of prion transmission via surgical instruments
Infectivity of human tissues
Efficacy of removing microbes by cleaning
Prion inactivation studies
Risk associated with instruments

12. CJD: DISINFECTION AND STERILIZATION
Effectiveness must consider both removal by cleaning and inactivation
Probability of a device remaining capable of transmitting disease depends on the initial contamination and effectiveness of C/D/S.
Cleaning results in a 4 log10 reduction of microbes and ~2 log10 reduction in protein contamination

13. CJD: DISINFECTION AND STERILIZATION
Rationale for US recommendations
Epidemiological studies of prion transmission
Epidemiological studies of prion transmission via surgical instruments
Infectivity of human tissues
Efficacy of removing microbes by cleaning
Prion inactivation studies
Risk associated with instruments

14. Non-Enveloped Viruses
Decreasing Order of Resistance of Microorganisms to Disinfectants/Sterilants
Prions
Spores
Mycobacteria
Non-Enveloped Viruses
Fungi
Bacteria
Enveloped Viruses

15. Ineffective or Partially-Effective Disinfectants: CJD
Alcohol
Ammonia
Chlorine dioxide
Formalin
Glutaraldehyde
Hydrogen peroxide
Iodophors/Iodine
Peracetic acid
Phenolics

16. Ineffective or Partially Effective Processes: CJD
Gases
Ethylene oxide
Formaldehyde
Physical
Dry heat UV
Microwave
Ionizing
Glass bead sterilizers
Autoclave at 121oC, 15m

17. Effective Disinfectants (>4 log10 decrease in LD50 with 1 hour)
Sodium hydroxide
1 N for 1h (variable results)
Sodium hypochorite
5000 ppm for 15m
Guanidine thiocyanate 4M
Phenolic (LpH)
0.9% for 30m

18. Effective Processes: CJD
Autoclave
134oC-138oC for 18m (prevacuum)
132oC for 60m (gravity)
Combination (chemical exposure then steam autoclave, potentially deleterious to staff, instruments, sterilizer)
Soak in 1N NaOH, autoclave 134oC for 18m
Soak in 1N NaOH, autoclave 121oC for 30m

19. CJD: DISINFECTION AND STERILIZATION
Rationale for US recommendations
Epidemiological studies of prion transmission
Epidemiological studies of prion transmission via surgical instruments
Infectivity of human tissues
Efficacy of removing microbes by cleaning
Prion inactivation studies
Risk associated with instruments

20. Disinfection and Sterilization
EH Spaulding believed how an object will be D/S depended on the objects intended use
CRITICAL-objects that enter normally sterile tissue or the vascular system should be sterile
SEMICRITICAL-objects that touch mucous membranes or skin that is not intact requires a disinfection process (high level disinfection) that kills all but bacterial spores (prions?)
NONCRITICAL-objects that touch only intact skin require low-level disinfection

21. CJD : potential for secondary
spread through contaminated
surgical instruments

22. Risk Assessment: Patient, Tissue, Device
Known or suspected CJD or other TSEs
Rapidly progressive dementia
Dura mater transplant, HGH injection
Tissue
High risk-brain, spinal cord, eyes
Device
Critical or semicritical

23. Examples: CJD D/S
High risk patient, high risk tissue, critical/semicritical device-special prion reprocessing
High risk patient, low/no risk tissue, critical/semicritical device-conventional D/S
Low risk patient, high risk tissue, critical/semicritical device-conventional D/S
High risk patient, high risk tissue, noncritical device-conventional disinfection

24. Conclusions
Epidemiologic evidence suggests nosocomial CJD transmission via medical devices is very rare
Guidelines based on epidemiologic evidence, tissue infectivity, risk of disease via medical devices, and inactivation data
Risk assessment based on patient, tissue and device
Only critical/semicritical devices contacting high risk tissue from high risk patients require special prion reprocessing

25. CJD: Disinfection and Sterilization Conclusions
Cleaning with special prion reprocessing
NaOH and steam sterilization (e.g., 1N NaOH 1h, 121oC 30 m)
134oC for 18m (prevacuum)
132oC for 60m (gravity)
No low temperature sterilization technology effective
Four disinfectants (e.g., chlorine) effective (4 log decrease in LD50 within 1h)

26. CJD: Sterilization in Health Care
Used Instrument 
Keep Wet (do not let tissue/fluid dry)
Clean (Washer Disinfector)
Steam Sterilize (NaOH and SS; 134oC, 18 min)
Sterile Instrument

27. CJD: Environmental Surfaces
High/Low/No Risk Tissue, High Risk Patient, Noncritical Surface/Device
Environmental surfaces contaminated with high risk tissues (autopsy table in contact with brain tissue) should be cleaned and then spot decontaminated with a 1:10 dilution of bleach
Environmental surfaces contaminated with low/no risk tissue require only routine disinfection

28. CJD: Disinfection and Sterilization Topics
Rationale for US recommendations
Epidemiological studies of prion transmission
Infectivity of human tissues
Efficacy of removing microbes by cleaning
Prion inactivation studies
Recommendations to prevent cross-transmission from medical devices contaminated with prions
Methodology-how methodology affects results

29. Non-Enveloped Viruses
Decreasing Order of Resistance of Microorganisms to Disinfectants/Sterilants
Prions
Spores
Mycobacteria
Non-Enveloped Viruses
Fungi
Bacteria
Enveloped Viruses

30. Prion Inactivation Studies
Problems
Investigators used aliquots of brain tissue macerates vs. intact tissue (smearing, drying); weights of tissue (50mg-375mg)
Studies do not reflect reprocessing procedures in a clinical setting (e.g., no cleaning)
Factors that affect results include: strain of prion (22A), prion conc in brain tissue, animal used, exposure conditions, validation and cycle parameters of sterilizers, resistant subpopulation, different test tissues, different duration of observations, screw cap tubes with tissue (air), etc

31. STERILIZATION Factors affecting the efficacy of sterilization
Bioburden
Cleaning
Pathogen type
Protein and salt
Biofilm accumulation
Lumen length and diameter
Restricted flow

34. Penicylinders Sterilized by Various Low-Temperature Sterilization Methods
Challenge: 12/ %ETO HCFC-ETO Sterrad
10% Serum,
0.65% Salt
(7 organisms, N=63) 97% % 95.2% 37%
No Serum or Salt,
(3 organisms, N=27) 100% 100% 96% 100%
Alfa et al. Infect Cont Hosp Epidemiol 1996;17: The three organisms included: E. faecalis, M. chelonei, B. subtilis spores. The seven organisms included: E. faecalis, P. aeruginosa, E.coli, M. chelonei, B. subtilis spores, B. stearothermophilus spores, B. circulans spores

36. Lumens Sterilized by Various Low-Temperature Sterilization Methods
Challenge: 12/ %ETO HCFC-ETO Sterrad
10% Serum,
0.65% Salt
(7 organisms, N=63) 44% 39.7% 49.2% 35%
No Serum or Salt,
(3 organisms, N=27) ND 96.3% 96.3% ND
Alfa et al. Infect Cont Hosp Epidemiol 1996;17: The three organisms included: E. faecalis, M. chelonei, B. subtilis spores. The seven organisms included: E. faecalis, P. aeruginosa, E.coli, M. chelonei, B. subtilis spores, B. stearothermophilus spores, B. circulans spores

37. Low-Temperature Sterilization Technologies (LTST) Conclusions
All technologies have limitations
LTST (ETO, HP gas plasma) demonstrate a significant number of failures in presence of serum or salt
Salt and serum provide protection for spores and bacteria
Salt and serum combined with a narrow lumen provide extraordinary protection with LTST

38. STERILIZATION Factors affecting the efficacy of sterilization
Bioburden
Cleaning
Pathogen type
Protein and salt
Biofilm accumulation
Lumen length and diameter
Restricted flow

39. Effect of Rinsing with Water on Sterilization Results
Method
Inoculate scalpel blade with tissue culture media with 10% fetal bovine serum containing 1.5x106 Geobacillus stearothermophilus spores dried for 12 hours at room temperature

45. Removal of Soil and Microorganisms from Medical Devices
Method
Inoculate 0.02 ml of FBS containing 106 B. stearothermophilus spores onto scalpel blade
Dry for 30 min at 35oC followed by 30 min at RT
Samples placed in distilled water at room temperature for specified time
Chloride, protein and spore concentration measured

47. Removal of Soil and Microorganisms from Medical Devices Conclusions
Inorganic, organic and microbial contaminants on a device are dramatically reduced during a washing process
96.3% (or 2.5 x 106 organisms) removed from blade in 150 sec

49. Removal of Soil and Microorganisms from Medical Devices Conclusions
Inorganic, organic and microbial contaminants on a device are dramatically reduced during a washing process
Contact with water for short period of time rapidly leads to the dissolution of salt crystals. Studies in 1950’s and 1960’s show that spores occluded inside crystals were very resistant to sterilization (e.g., ETO, steam).
Minimal cleaning eliminates the effect of salt
Simulated use tests that do not include washing would not represent conditions that exist in use situation

51. without sterilization
You can clean
without sterilization
but you NEVER
can sterilize
without cleaning

52. Conclusions All sterilization processes effective in killing spores
Salt favors crystal formation and impairs sterilization by occlusion of organisms
Cleaning removes salts and proteins and must precede sterilization
Failure to clean or ensure exposure of microorganisms to sterilant (e.g. connectors) could affect effectiveness of sterilization process
CJD inactivation studies should be consistent with actual clinical practice

53. CJD: Disinfection and Sterilization Topics
Rationale for US recommendations
Epidemiological studies of prion transmission
Infectivity of human tissues
Efficacy of removing microbes by cleaning
Prion inactivation studies
Recommendations to prevent cross-transmission from medical devices contaminated with prions
Methodology-how methodology affects results

54. Thank you

55. References
Alfa MJ, Olson N, DeGagne P, Hizon R. New low temperature sterilization technologies: Microbicidal activity and clinical efficiency. In Rutala WA, ed. Disinfection, Sterilization, and Antisepsis in Healthcare. Champlain, NY: Polyscience Publications. 1998:67-78.
Rutala WA, Weber DJ. Clinical effectiveness of low-temperature sterilization technologies. Infect Control Hosp Epidemiol 1998;19:
Jacobs P. Cleaning: principles and benefits. In: Rutala WA, ed. Disinfection, Sterilization, and Antisepsis in Healthcare. Champlain, NY: Polyscience Publications. 1998:

56. Disinfection and Sterilization for Prion Diseases References
Rutala WA, Weber DJ. Creutzfeldt-Jakob Disease: Recommendations for Disinfection and Sterilization. Clin Inf Dis 2001;32:
Rutala WA, Weber DJ, and HICPAC. CDC Guideline for Disinfection and Sterilization. In preparation
Weber DJ, Rutala WA. Managing the risks of nosocomial transmission of prion diseases. Current Opinions in Infectious Diseases. 2002;15:

57. Prevent Patient Exposure to CJD Contaminated Instruments
How do you prevent patient exposure to neurosurgical instruments from a patient who is latter given a diagnosis of CJD?
Hospitals should use the special prion reprocessing precautions for instruments from patients undergoing brain biopsy when a specific lesion has not been demonstrated (e.g., CT, MRI). Alternatively, neurosurgical instruments used in such cases could be disposable.

58. vCJD: Disinfection and Sterilization
To date no reports of human-to-human transmission of vCJD by blood or tissue
Unlike CJD, vCJD detectable in lymphoid tissues and prior to onset of clinical illness
Special prion reprocessing (or single use instruments) proposed in the UK in dental, eye, or tonsillar surgery on high risk patients for CJD or vCJD
If epidemiological and infectivity data show these tissues represent a transmission risk then special prion reprocessing could be extended to these procedure

59. Factors Affecting the Efficacy of LTST
Cleaning - Failure to clean results in higher bioburden, protein load and salt concentration
Bioburden - Natural bioburden on surgical devices 100 to 103
Pathogen - Spore forming organisms most resistant
Protein - Residual protein decreases efficacy of sterilization
Salt - Residual salt decreases efficacy of sterilization