Prion Disease and Medical Devices

Abstract

Prions are novel proteinaceous-infectious agents that have been implicated in transmissible spongiform encephalopathies. It is now generally accepted that noninfectious prion proteins are normally produced by the host and may undergo a conformational change to an abnormal, pathologic form, which appears to be responsible for disease symptoms. Many methods of decontamination and sterilization are claimed to be ineffective against prion proteins. Incidences of iatrogenic transmission of prions due to medical devices have been reported, and the recommended clinical practices when handling suspected cases are reviewed. Recent results with a peracetic acid based sterilant indicate that it may be a safe and effective means of prion inactivation on medical devices.

Transmission of Infection by Flexible Gastrointestinal Endoscopy and Bronchoscopy

“…Most contemporary flexible endoscopes cannot be heat sterilized and disinfected with high concentrations of disinfectants without severe damage (1,9). Therefore, flexible endoscopes should be discarded after endoscopy in patients with CJD (205).…”

The Challenge of Prion Decontamination

“…A recent example of these effects with use of peracetic acid has been described. Previous testing with peracetic acid was conducted with the biocide alone (in the absence of any liquid formulation) and was shown to be ineffective [16]; however, more recent reports indicate that peracteic acid in a liquid formulation has shown promising activity against prions, though this requires further confirmation [17]. At the same time, use of certain active agents should be contraindicated; in particular, biocides that can potentially cross-link proteins (including formaldehyde, glutaraldehyde, and ortho-phthalaldehyde) should not be used to decontaminate prion-infected materials or devices.…”

Quantitative evaluation of prion inactivation comparing steam sterilization and chemical sterilants: proposed method for test standardization

“…23 One in vitro assay showed a peracetic-acid-induced decrease in prion protein, but the protein was not completely eliminated so it is likely that potential infectivity remained. 24 Indeed, an immunoblot assay is not sufficiently sensitive to evaluate the efficiency of a product. 25 Animal inoculations appear to be a standardizable method for the evaluation of prion inactivation in a sample, providing that a 15-month incubation is acceptable, in order to guarantee the total absence of residual infectivity.…”