The Principles of Medical Device Decontamination

Transmissible Spongiform Encephalopathies 8 (TSE’s) by contrast are caused by misfolded prion proteins being passed from one person or species to another although the process is not entirely understood. Transmission has been via ingestion of meat, particularly processed as in variant Creutzfeldt-Jacob Disease (vCJD) but also through human meat consumption (kuru), by blood (vCJD), through mutation direct in the brain in sporadic CJD (sCJD), via tissue transplantation (sCJD) e.g. corneal transplants and in rarer genetic forms of TSE e.g. Fatal Familial Insomnia. Once the abnormal prion protein presents to the brain, normal prion protein as it is made in the brain uses the acquired abnormal protein as a template and lays down sheets of the protein (amyloid) that leads to degenerative brain disease, which is inevitably fatal. The decontamination community is therefore particularly interested in these replicating proteins that are capable of being transmitted by body tissues and medical devices. These transmissible proteins remain an ongoing, if not entirely quantified threat. Gill et al 9 estimated the prevalence of vCJD in the UK population as 493 per million population. The potential threat from vCJD compared to sCJD or familial forms, is that the risk tissues are not limited just to the central nervous system but also include lymphoid tissue distributed throughout the body. For the decontamination professional, proteins are more difficult to remove and destroy and have required the UK to continue to be concerned about protein removal. This is the reasoning behind keeping instruments moist before reprocessing, and to ensure systems remove protein with use of protein detection methodology during validation and audit of the decontamination processes.

Difficulty of cleaning and/or protein removal has led to increased single use instruments being utilised to manage these risks e.g. dental reamers, ophthalmic tonometers or where the patient has a risk of CJD.

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