Enzyme Technology Reduces Risk of Transmitting Prions Through Contaminated Surgical Instruments
In Europe, a commercial enzyme product is now available to destroy prions that may contaminate surgical instruments. Prions are tiny “proteinaceous infectious particles” that have been linked to Bovine Spongiform Encephalopathy, or “mad cow disease,” and its human form, variant Creutzfeldt-Jakob Disease (vCJD).[1]
Surgical instrument.
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A degenerative, fatal neurological disease, vCJD has a long incubation period (perhaps a decade or more). Diagnostic tests that can reliably detect the disease before the onset of symptoms are not yet available.
Incidence
Most cases of vCJD (about 180 cases worldwide) have occurred in the UK and elsewhere in Europe. According to the Creutzfeldt-Jakob Disease Surveillance System, Canada has had only one known reported case of vCJD.[2]
Much attention has focused on the link between consumption of contaminated beef and the subsequent development of vCJD. However, person-to-person transmission of vCJD through surgical instruments has also come under scrutiny due to the ability of prions to bind to stainless steel and survive most standard methods of disinfection and sterilization.[3]
Of particular concern are surgeries involving tissues where prions accumulate, such as the brain, spinal cord, eyes, appendix, and tonsils. Some hospitals have introduced policies for using single-use (disposable) instruments, wherever possible.[4]
How it Works
In an additional “pre-soak” step during surgical instrument sterilization, Prionzyme™ (Genencor International) is used in combination with specific temperature and pH conditions to break down the chemical bonds in the prion protein molecules. Unlike many other disinfectants and sterilization processes, enzyme-based products do not corrode surgical instruments or pose a hazard to health care staff.[5]
Regulatory Status
Prionzyme is not yet available in Canada. The first Prionzyme product designed for use on surgical instruments is now commercially available in Europe.[1] Similar products are in development for use on dental instruments and for equipment used in the meat processing industry.
The Evidence
Studies in mice have provided data to support the European Union marketing of Prionzyme. According to Genencor, these studies showed a ten millionfold decrease in prion infectivity.[1]
Cost
The price of Prionzyme is unpublished, but may be obtained upon request from Genencor International.
Future Steps
The magnitude of the potential risk for the spread of vCJD through surgical instruments is still unknown. However, the costs associated with the use of disposable surgical instruments are considerable. Products that can improve the decontamination of surgical instruments may offer a more cost-effective and environmentally sound alternative, but studies to assess these options are needed.
References
[1] Prionzyme: a general backgrounder. Palo Alto (CA): Genencor International; 2006. Available: http://www.genencor.com/pdf/Prionzyme%20Backgrounder%20(final).pdf
[2] CJD deaths reported to CJD-SS, 1994-2005. In: Creutzfeldt-Jakob Disease Surveillance System (CJD-SS). Ottawa: Public Health Agency of Canada; 2006. Available: http://www.phac-aspc.gc.ca/hcai-iamss/cjd-mcj/cjdss-ssmcj/stats_e.html
[3] Dunstan RA, et al. Aust N Z J Public Health 2005;29(4):308-12.
[4] Frosh A, et al. BMJ 2001;322(7302):1558-9. Available: http://bmj.bmjjournals.com/cgi/reprint/322/7302/1558