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Disinfection studies with two strains of mouse-passaged scrapie agent. Guidelines for Creutzfeldt-Jakob and related
Abstract:
A variety of disinfection procedures were tested on two strains of scrapie agent, treated either as brain macerates (autoclaving) or as 10% homogenates (chemical treatments). It is suggested that a given treatment should produce a titre loss, of both strains of scrapie, of at least 10(4) units before it be regarded as useful for the disinfection of the agents of scrapie and Creutzfeldt-Jakob disease (CJD). By this criterion, treatment at room temperature with about 4% Hycolin (0.6% chlorinated phenols), 0.2% permanganate, 5% Tego (dodecyl-di(aminoethyl)-glycine) or 5% sodium dodecyl sulphate (SDS) are unsuitable. However, data indicate that SDS might be used to reduce the heat stability of scrapie agent. Hypochlorite (Sterilex) was the only satisfactory chemical reagent tested. At least 10(4)-10(5) units of infectivity were lost by treatment with hypochlorite containing 1,000 ppm available chlorine after a 4-16 h exposure, or containing 10,000 ppm available chlorine after a half-hour exposure. The latter result points to the use of concentrated hypochlorite (about 2% available chlorine; approximately 20% Sterilex) to decontaminate surfaces. We suggest that the cleaning action of SDS, or other strong detergents, might also help to decontaminate surfaces, but studies on this are needed. Autoclaving at 126 degrees C for 1-2 h reduced titres by 10(3)-10(7) units, depending on the strain of agent. However, total disinfection of brain containing high titres of infectivity was approached only at 136 degrees C when titre losses of about 10(6) units were obtained by autoclaving for 4-32 min. Further studies are needed before we can make simple, general recommendations for the disinfection of CJD agents in hospital practice.
Insights
Effective disinfection of scrapie and Creutzfeldt-Jakob disease (CJD) agents requires significant titre loss. Concentrated hypochlorite and high-temperature autoclaving show promise for decontamination, but further research is needed for hospital practices.
Area of Science:
- Neuroscience
- Infectious Diseases
- Biochemistry
Background:
- Scrapie and Creutzfeldt-Jakob disease (CJD) are transmissible spongiform encephalopathies caused by prions.
- Effective disinfection protocols are crucial for preventing prion disease transmission in healthcare settings.
- Limited data exist on the efficacy of various disinfectants against scrapie and CJD agents.
Purpose of the Study:
- To evaluate the efficacy of different disinfection procedures against two strains of scrapie agent.
- To determine the required titre loss for effective disinfection of scrapie and CJD agents.
- To identify suitable disinfectants for prion decontamination in laboratory and clinical settings.
Main Methods:
- Testing autoclaving and chemical treatments on scrapie agent in brain macerates and homogenates.
- Assessing titre loss after exposure to various disinfectants including Hycolin, permanganate, Tego, sodium dodecyl sulphate (SDS), and hypochlorite.
- Evaluating the effect of autoclaving at different temperatures and durations on scrapie agent infectivity.
Main Results:
- Sodium dodecyl sulphate (SDS) and other tested chemicals (Hycolin, permanganate, Tego) were unsuitable for disinfection, though SDS may reduce heat stability.
- Hypochlorite (Sterilex) was the only effective chemical disinfectant, achieving significant titre loss at high concentrations and sufficient exposure times.
- Autoclaving at 126°C reduced titres, but complete disinfection of high-titre samples required autoclaving at 136°C.
Conclusions:
- Concentrated hypochlorite solutions are recommended for surface decontamination of prion agents.
- High-temperature autoclaving (136°C) is necessary for effective disinfection of heavily contaminated materials.
- Further research is required to establish simple, general recommendations for CJD agent disinfection in clinical practice.
