Limited efficacy of steam sterilization to inactivate vCJD infectivity

• Published in: The Journal of hospital infection 2012-01, Vol.80 (1), p.46-51
• Main Authors: Fernie, K, Hamilton, S, Somerville, R.A
• Format: Article
• Language: English
• Subjects: Animals; Autoclaving; Biological and medical sciences; BSE; Cattle; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Iatrogenic transmission; Infectious Disease; Infectious diseases; Medical sciences; Neurology; Prions - pathogenicity; Prions - radiation effects; Resistance; Steam; Steam sterilization; Sterilization - methods; Temperature; Time Factors; United Kingdom; vCJD
• ISSN: 0195-6701; 1532-2939
• DOI: 10.1016/j.jhin.2011.09.004

Summary Background The transmission of bovine spongiform encephalopathy (BSE) to humans as variant Creutzfeldt–Jakob Disease (vCJD) raised concerns about potential secondary transmissions due to the resistance of the agents causing transmissible spongiform encephalopathies (TSEs), sometimes known as prions, to commonly used methods of sterilization, notably steam sterilization (or autoclaving). It has been suggested that surgical instruments and other medical devices might retain sufficient infected tissue debris after cleaning and steam sterilization to infect patients on whom they are subsequently used. Aim To determine whether concerns about the lack of efficacy of steam sterilization of vCJD were justified. Methods The reduction in infectivity of brain macerates of vCJD brain after steam sterilization using the standard temperatures and time recommended for autoclaving in UK hospitals (134–137 °C for 3 min) was measured. Findings Reductions in titre of 102.3 to >103.6 ID50 were found. In three of four samples, infectivity was recovered after steam sterilization. Conclusion As noted previously, TSE strains derived from BSE sources appear to be more resistant to steam sterilization and other forms of heat inactivation than other TSE sources.