Questions and Answers:
Creutzfeldt-Jakob Disease Infection-Control Practices
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What is Creutzfeldt-Jakob
disease?
Creutzfeldt-Jakob disease (CJD) is a rapidly progressive,
invariably fatal neurodegenerative disorder believed
to be caused by an abnormal isoform of a cellular glycoprotein
known as the prion protein. CJD occurs worldwide and
the estimated annual incidence in many countries, including
the United States, has been reported to be about one
case per million population.
The vast majority of CJD patients usually die within
1 year of illness onset. CJD is classified as a transmissible
spongiform encephalopathy (TSE) along with other prion
diseases that occur in humans and animals. In about
85% of patients, CJD occurs as a sporadic disease with
no recognizable pattern of transmission. A smaller
proportion of patients (5 to 15%) develop CJD because
of inherited mutations of the prion protein gene. These
inherited forms include Gerstmann-Straussler-Scheinker
syndrome and fatal familial insomnia.
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How is CJD
diagnosed?
Physicians suspect a diagnosis of CJD on the basis
of the typical signs and symptoms and progression of
the disease. In most CJD patients, the presence of
14-3-3 protein in the cerebrospinal fluid and/or a
typical electroencephalogram (EEG) pattern, both of
which are believed to be diagnostic for CJD, have been
reported. However, a confirmatory diagnosis of CJD
requires neuropathologic and/or immunodiagnostic testing
of brain tissue obtained either at biopsy or autopsy.
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Have
there been any reports of iatrogenic transmission of
CJD?
Yes, iatrogenic transmission of the CJD agent has
been reported in over 250 patients worldwide. These
cases have been linked to the use of contaminated human
growth hormone, dura mater and corneal grafts, or neurosurgical
equipment. Of the six cases linked to the use of contaminated
equipment, four were associated with neurosurgical
instruments, and two with stereotactic EEG depth electrodes.
All of these equipment-related cases occurred before
the routine implementation of sterilization procedures
currently used in health care facilities. No such cases
have been reported since 1976, and no iatrogenic CJD
cases associated with exposure to the CJD agent from
surfaces such as floors, walls, or countertops have
been identified.
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How should
surgical instruments used on suspected or confirmed
CJD patients be reprocessed?
Inactivation studies have not rigorously evaluated
the effectiveness of actual cleaning and reprocessing
methods used in health care facilities. Recommendations
to reprocess instruments potentially contaminated with
the CJD agent are primarily derived from in vitro inactivation
studies that used either brain tissues or tissue homogenates,
both of which pose enormous challenges to any sterilization
process.
The World Health Organization (WHO) has developed CJD
infection control guidelines that can be a valuable
guide to infection control personnel and other health
care workers involved in the care of CJD patients.
Destruction of heat-resistant surgical instruments
that come in contact with high infectivity tissues,
albeit the safest and most unambiguous method as
described in the WHO guidelines, may not be practical
or cost effective.
One of the three most stringent chemical and autoclave sterilization methods outlined in Annex III of the WHO guidelines (see below) should be used to reprocess heat-resistant instruments that come in contact with high infectivity tissues (brain, spinal cord, and eyes) and low infectivity tissues (cerebrospinal fluid, kidneys, liver, lungs, lymph nodes, spleen, olfactory epithelium, and placenta) of patients with suspected or confirmed CJD. High and low infectivity tissues were defined on the basis of available experimental data as described in Table 2 of the WHO guidelines. The stringent sterilization methods described below should be used to reprocess medical instruments that come in contact with high infectivity tissues of persons known to be blood relatives of patients with inheritable forms of TSEs. In addition, instruments should be kept moist and not allowed to air dry throughout the surgical procedure by immersing them in water or disinfectant solution.
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What are the most stringent chemical and autoclave sterilization methods outlined in Annex III of the WHO infection control guidelines for transmissible spongiform encephalopathies?
The three most stringent sterilization methods for heat-resistant instruments described in Annex III of the WHO guidelines are listed below; the methods are listed in order of more to less severe treatments. Sodium hypochlorite may be corrosive to some instruments, such as gold-plated instruments. Before instruments are immersed in sodium hypochlorite, the instrument manufacturer should be consulted about the instrument's tolerance of exposure to sodium hypochlorite. Instruments should be decontaminated by a combination of the chemical and recommended autoclaving methods before subjecting them to cleaning in a washer cycle and routine sterilization.
- Immerse in a pan containing 1N sodium hydroxide
(NaOH) and heat in a gravity displacement autoclave
at 121°C for 30 min; clean; rinse in water; and
subject to routine sterilization.
[CDC NOTE: The pan containing sodium hydroxide should be covered, and care
should be taken to avoid sodium hydroxide spills in the autoclave. To avoid
autoclave exposure to gaseous sodium hydroxide condensing on the lid of the
container, the use of containers with a rim and lid designed for condensation
to collect and drip back into the pan is recommended. Persons who use this
procedure should be cautious in handling hot sodium hydroxide solution (post-autoclave)
and in avoiding potential exposure to gaseous sodium hydroxide, exercise
caution during all sterilization steps, and allow the autoclave, instruments,
and solutions to cool down before removal. An experiment conducted by Food
and Drug Administration (FDA) investigators indicated that the use of appropriate
containment pans and lids prevents escape of sodium hydroxide vapors that
may cause damage to the autoclave (Brown and Merritt. Am J Infect Control
2003;31:257-260). PDF
version  (86
KB)]
- Immerse in 1N NaOH or sodium hypochlorite (20,000
ppm available chlorine) for 1 hour; transfer instruments
to water; heat in a gravity displacement autoclave
at 121°C for 1 hour; clean; and subject to routine
sterilization.
[CDC NOTE: Sodium hypochlorite may be corrosive to some instruments.]
- Immerse in 1N NaOH or sodium hypochlorite (20,000
ppm available chlorine) for 1 hour; remove and rinse
in water, and then transfer to open pan and heat
in a gravity displacement (121°C) or porous load
(134°C) autoclave for 1 hour; clean; and subject
to routine sterilization.
[CDC NOTE: Sodium hypochlorite may be corrosive to some instruments.]
FDA investigators evaluated the effects to surgical
instruments of the steps involved in the sterilization
protocols listed above; some of the protocols they
assessed subjected the instruments to harsher conditions
than those prescribed above. Their findings indicate
that much of the damage from autoclaving in sodium
hydroxide was cosmetic and would not affect the performance
or cleaning of the instruments. Soaking in sodium hydroxide
had the least damaging effect on instruments, but immersion
in sodium hypochlorite bleach caused severe damage
to some instruments. The article summarizing the findings
of this experiment by Brown et al. of the FDA was published
in the Journal of Biomedical Materials Research (electronic
version published October 2004) PDF
version (191
KB/5 pages).
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How
should instruments used in patients with no clear diagnosis
at the time of a neurosurgical procedure be reprocessed?
In some patients undergoing neurosurgery, a CJD diagnosis
that is not suspected before the procedure may be confirmed
after the neurosurgery. For this group of patients,
in whom the clinical diagnosis leading to the neurosurgical
procedure remains unclear, the instruments should be
reprocessed in the same manner as that for instruments
used in procedures involving suspected or confirmed
CJD patients. Unless a clear non-CJD diagnosis is established,
these patients should be considered as potentially
suspected CJD patients for all other infection control
requirements.
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How
should heat-sensitive instruments or materials that
come in contact with suspected or confirmed CJD patients
be decontaminated?
All disposable instruments, materials, and wastes
that come in contact with high infectivity tissues
(brain, spinal cord, and eyes) and low infectivity
tissues (cerebrospinal fluid, kidneys, liver, lungs,
lymph nodes, spleen, and placenta) of suspected or
confirmed TSE patients should be disposed of by incineration.
Surfaces and heat-sensitive re-usable instruments that
come in contact with high infectivity and low infectivity
tissues should be decontaminated by flooding with or
soaking in 2N NaOH or undiluted sodium hypochlorite
for 1 hour and rinsed with water.
[CDC NOTE: Sodium hypochlorite may be corrosive to some instruments.]
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What
kinds of precautions should be taken while embalming
the bodies of patients with suspected or confirmed
CJD?
An autopsied or traumatized body of a suspected or
confirmed CJD patient can be embalmed, using the precautions
outlined in the WHO CJD
infection control guidelines. CJD patients who
have not been autopsied or whose bodies have not been
traumatized can be embalmed using Standard Precautions.
Family members of CJD patients should be advised to
avoid superficial contact (such as touching or kissing
the patient's face) with the body of a CJD patient
who has been autopsied. However, if the patient has
not been autopsied, such contact need not be discouraged.
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Additional
recommendations for CJD infection control practices
not addressed in this Q&A
Obtain them from:
WHO
Infection Control Guidelines for Transmissible
Spongiform Encephalopathies: Report of a WHO Consultation,
Geneva, Switzerland, 23-26 March 1999." |
