April 1, 2013 (updated, February, 2015) — In October, 2000, a hospital reported that last spring as many as 8 patients may have been infected with Creutzfeldt-Jakob disease, or “CJD,” a rare and fatal neurological disease.(1)
Some of the same instruments used during brain surgery on an index patient in March, 2000, were reused on 8 other patients during various neurological procedures between March and May. The potentially contaminated surgical instruments were not removed from service until May, when the index patient who had passed away was found during autopsy to have had CJD.
Click here to select a book to read about Creutzfeldt Jakob disease.
Reports suggest that, after use on the index patient and each of the other 8 patients, the instruments were washed and sterilized in accordance with the hospitals routine decontamination procedures.
Prions, however, which are the agents thought to cause CJD, may survive standard cleaning and sterilization procedures, raising concern.
Therefore, the possibility exists, however remote, that the surgical instruments:
- were contaminated with prions during the index patients brain surgery in May;
- remained contaminated despite the hospitals efforts to clean and sterilize them; and
- between March and May transmitted prions, and therefore presumably CJD, to these 8 patients.
Complicating this incident is the lack of a reliable method to assess the risk that any of these 8 patients were infected with CJD. Symptoms of CJD may not develop for many years, and CJD usually can only be confirmed definitively through an autopsy or brain biopsy.
Update: A similar incident occurred more recently in New England. According to Reuters, “thirteen people who recently underwent neurosurgery in Massachusetts and New Hampshire may have been exposed to a rare and fatal brain condition similar to ‘mad cow’ disease because of potentially infected surgical instruments.” Click here to read this Reuters report, dated 09-05-2013.
Click here to read Dr. Muscarella’s related blog — “New Hampshire Patient Likely Died of Creutzfeltd-Jakob Disease” — about this incident in New England (09-05-2013).
Although this incident occurred in 2000, its discussion, risk assessment, and recommendations remain germane today.
In addition to the notification of patients of the risk of transmission of CJD’s infectious prions during surgery, in September, 2013, health officials in Canada, in August, 2012, met with nearly 150 surgical patients of St. Joseph’s Hospital (in Saint John, Canada) to reassure them they had not been exposed to CJD, despite a confirmed case at this hospital in July (2012).
As a precaution, this hospital’s operating rooms were closed for two days to be disinfected. Click here to read more about this incident.
What is “CJD”?
CJD, or Creutzfeltd-Jakob disease, is a fatal degenerative neurological disorder that causes structural changes in human brain tissue. Initial symptoms include depression and poor memory, followed in its latter stages by dementia and loss of physical functioning. Currently there is no treatment for CJD.(2)
Creutzfeltd-Jakob disease is a fatal degenerative neurological disorder for which there currently is no treatment. — Lawrence F Muscarella PhD
CJD is a transmissible subacute spongiform encephalopathy (TSE) that affects approximately 1 in 1 million people per year. Examples of other TSEs include bovine spongiform encephalopathy (BSE), or mad cows disease, and scrapie, which infects goats and sheep.
Most cases of CJD occur sporadically,(2) although as many as 15% of all cases may be inherited.(3,4) Less than 5% of CJD cases result from contact with contaminated surgical instruments, tainted hormones from the pituitary gland, and infected neurological tissue.
Quality and Safety Services for Hospitals, Manufacturers, Patients: Click here to read about Dr. Muscarella’s quality and safety services committed to reducing the risk of healthcare-associated infections, including CRE outbreaks linked to contaminated endoscopes and other reusable medical equipment.
What is a prion?
Prions, the causative agents of CJD, are believed to be infectious proteins unusually resistant to standard cleaning and sterilization methods.
Looking to read a book about the scourge of prions. Click the link.
Unlike all other known pathogens, prions do not contain genetic material.
Prions are produced in cells through the processes known as transcription and translation. Genes on a specific portion of a DNA molecule ordinarily instruct the cell to synthesize healthy proteins. Cellular messengers attach to and transport amino acids (the building blocks of proteins) from the cells cytoplasm to its ribosomes, where protein synthesis occurs. The retrieved amino acids are assembled into a specific order determined by the genes instructions.
Click here to select a book to read about the history of transmissible subacute spongiform encephalopathies.
Like a chain-linked fence, these amino acids bond to one another, forming a protein molecule. For unclear reasons, a mutated or altered gene can cause the sequence of assembled amino acids to become out of order.(5,6) The result can be the production of unhealthy and infectious proteins, or prions.
Because gastrointestinal endoscopes do not contact prion-containing tissue or secretions, and even trace contamination would be reduced or eliminated with simple mechanical cleaning, thus rendering any potential inoculum far below the threshold for oral acquisition, infection control experts have stated that currently accepted cleaning and disinfection protocols should be adequate for reprocessing endoscopes. — Douglas Nelson, M.D., Lawrence F Muscarella, PhD (click here)
What decontamination method effectively destroys prions?
Reports indicate that prions can be transmitted from one patient to another via contaminated surgical instruments.(2,7,8) Surprisingly, standard processes routinely used to destroy virtually all known pathogens, such as those that use ethylene oxide gas, glutaraldehyde, peracetic acid – and even heat – are reported to be ineffective against prions.(2)
And while it reduces bioburden, cleaning may not always effectively remove all of the prions from a contaminated instrument.(2) Although some decontamination methods are recommended for items potentially contaminated with prions, data demonstrating their respective effectiveness are limited.
The minimum requirements for decontaminating surgical instruments potentially contaminated with prions is unclear. Nevertheless, there are at least four available options:(2,9-11)
- Use only disposable surgical instruments;
- Reprocess surgical instruments using a pre-vacuum steam sterilization cycle at 135 degrees C (275 degrees F) for 18 minutes; or instead
- Use a standard gravity steam sterilization cycle at 132 degrees C (270 degrees F) for 60 minutes. Both options #2 and #3 have been reported to be effective against prions; and
- Rather than reprocessing and reusing reusable instruments, incinerate them.
Cleaning, exposing instruments to sodium hydroxide (1N, NaOH, or soda lye) or sodium hypochlorite (NaOCl, or bleach) for 60 minutes, followed by a standard gravity steam cycle, is also an option.(2) Combining two or more different procedures appears to be most effective.(2,12) — Lawrence F Muscarella, PhD
Assessing the risk of prion transmission during surgery
Algorithms designed to assess the risk of prion transmission are helpful, if limited in their usefulness. Without a reliable screening method for CJD, taking precautionary measures to avert CJD infection becomes problematic.
Employing a policy that assumes every patient is a CJD-carrier seems unrealistic. To be clear, the risk of being contaminated with prions during surgery is remote. According to the Centers for Disease Control and Prevention (CDC), no reports of CJD transmission during surgery have been reported during the past 30 years.
Further, only patients exposed to high-risk tissues, such as pituitary gland hormones, the brain’s dura mater, spinal cord, cornea, and other types of neurological tissues, are reported to be at risk for CJD.(1) To date, CJD following endoscopy has not been reported. — Lawrence F Muscarella, PhD
Four scenarios are described below. The first presents the greatest risk of CJD infection, the fourth the least risk. These scenarios, which describe the types of instruments used (simple or complex in design?) and the types of tissues encountered (at risk neurological tissues?), can be used to assess the risk of prion transmission during surgery:
1. Complex surgical instruments that are difficult to clean and in contact with at risk neurological tissues: Because these instruments pose the highest risk for transmitting prions, only disposables should be used;
2. Simple surgical instruments that are easy to clean and in contact with at risk neurological tissues: These instruments pose a risk for transmitting prions and therefore should be disposable. If, however, disposables are not available, then thorough cleaning followed by an extended sterilization procedure is recommended;
3. Complex surgical instruments that are difficult to clean and in contact with low risk tissues, such as the gastrointestinal and respiratory tracts: These instruments, which include biopsy forceps, pose a negligible risk of prion contamination (no reports of prion transmission during an endoscopic procedure have been reported).
The use of disposable instruments is recommended; but if impractical, reprocessing the instruments using normal sterilization procedures preceded by thorough cleaning will all but eliminate any risk of prion transmission; and
4. Simple instruments that are easy to clean and in contact with low risk tissues, such as the gastrointestinal or respiratory tracts: For these types of surgical (and critical) instruments, there is virtually no risk of prion transmission. Normal sterilization procedures preceded by thorough cleaning are recommended.
References are available upon request.
Article by Lawrence F Muscarella PhD: posted 4/1/2013; updated 9-1-2015.