Creutzfeldt-Jakob Disease (CJD) and the Challenges of Surgical Instrument Reprocessing

News / October 15, 2020

Creutzfeldt-Jakob disease (CJD), commonly referred to as the human equivalent of mad cow disease, is caused by rogue, misfolded protein aggregates termed prions, which are infectious and cause fatal damages in the patient’s brain. The Centers for Disease Control and Prevention (CDC) defines prions as “abnormal, pathogenic agents that are transmissible and are able to induce abnormal folding of specific normal cellular proteins called prion proteins that are found most abundantly in the brain.” 1

Patients infected with CJD develop signature microscopic sponge-like holes in their brains.  The initial signs of CJD include memory loss, behavior changes, movement disorder, and vision problems, which rapidly progress to death. Inter-personal CJD transmission has occurred after patients were exposed to surgical instruments previously contaminated by CJD brain tissues.

According to the National Institutes of Health (NIH), 90 percent of CJD patients die within one year of onset. Presently, there is no available treatment or cure for this deadly disease. 2

In a November, 2017 study, Case Western Reserve University School of Medicine researchers found that CJD patients also harbor infectious prions in their skin, albeit at lower levels than found in the brain. In the study, the researchers collected skin samples from 38 patients with assistance from the National Prion Disease Pathology Surveillance Center at Case Western Reserve School of Medicine and measured their prion levels.3

Using a highly sensitive in vitro assay developed at the NIH, the researchers at Case Western detected prion protein aggregates in the skin samples from all of the 38 CJD patients in the study. The researchers further demonstrated that such skin prions are infectious, since they are capable of causing disease in humanized mouse models.

It has long been known that CJD is transmissible via surgical instruments used on prion-infected brain tissue. These study findings raise a host of new issues and concerns for surgical instrument reprocessing.  This is because prions are incredibly resistant to most routine methods of decontamination and sterilization and they can easily survive normal reprocessing methods.

“Our finding of infectious prions in skin is important since it not only raises concerns about the potential for disease transmission via common surgeries not involving the brain, but also suggests that skin biopsies and autopsies may enhance pre-mortem and post-mortem CJD diagnosis,” said Wenquan Zou, Associate Professor of Pathology and Neurology and Associate Director of the National Prion Disease Pathology Surveillance Center at Case Western Reserve School of Medicine. 4

In the United States, the national standards on how to disinfect and sterilize medical equipment that has come into contact with prions (i.e. CJD) come from AAMI and are approved by the American National Standards Institute (ANSI) as American National Standards. According to the AAMI standards (ANSI/AAMI Standards ST-79 Annex C – Processing CJD-contaminated patient care equipment and environmental surfaces), the high resistance of prions to standard sterilization methods require special procedures in the reprocessing of surgical instruments.

The AAMI recommended process for reprocessing surgical instruments and medical equipment exposed to prions is referenced in the Guideline for Disinfection and Sterilization of Prion-Contaminated Medical Instruments, a whitepaper featured by The Society of Healthcare Epidemiology of America (SHEA). Their recommended guidelines are as follows:

• Instruments should be kept wet (e.g., immersed in water or a prionicidal detergent) or damp after use and until they are decontaminated, and they should be decontaminated (e.g., in an automated washer-disinfector) as soon as possible after use. Dried films of tissue are more resistant to prion inactivation by means of steam sterilization than are tissues that are kept moist.
• After the device is clean, it should be sterilized by either steam sterilization or using a combination of sodium hydroxide and autoclaving, using 1 of the 4 following options:
  • Option 1. Autoclave at 134°C for 18 minutes in a prevacuum sterilizer.
  • Option 2. Autoclave at 132°C for 1 hour in a gravity displacement sterilizer.
  • Option 3. Immerse in 1 N NaOH (1 N NaOH is a solution of 40 g NaOH in 1 L water) for 1 hour; remove and rinse in water, then transfer to an open pan and autoclave (121°C gravity displacement sterilizer or 134°C porous prevacuum sterilizer) for 1 hour.
  • Option 4. Immerse in 1 N NaOH for 1 hour and heat in a gravity displacement sterilizer at 121°C for 30 minutes, then clean and subject to routine sterilization.

Regretfully, as of this blog posting (9/4/2020), none of these options have been validated by independent laboratory testing to scientifically prove that they completely eradicating prions from surgical instruments and reusable medical equipment. What we do know is that flash sterilization should not be used in the case of prion-contaminated devices.

AAMI recommendations also emphasize that it is essential to ensure the prion-contaminated surgical instruments being processed are thoroughly decontaminated, cleaned and fully accessible to the sterilant. If the contaminated surgical instruments cannot be cleaned or exposed to steam and other sterilants, then they should be discarded, according to the AAMI recommendations.

Given this new, increased threat to patient safety from contaminated surgical instruments, the need for healthcare professionals to demand validated IFUs from their instrument manufacturers has never been greater. Asking for validated IFUs is a key step that they must take to reduce the risk of a contaminated instrument infecting one of their patients with a potentially life-threatening infection.

1 https://www.cdc.gov/

2 https://www.nih.gov/

3 ‘Researchers Find Infectious Prions in Creutzfeldt-Jakob Disease Patient Skin’ Case Western Reserve School of Medicine, Nov. 22, 2017

4 Op. Cite.