Miele & Cie. KG, Vertriebsgesellschaft Deutschland

Reprocessing with OxiVario Plus: 'In vivo' proof of prion decontamination

A year ago, the Miele OxiVario Plus reprocessing method used to produce high-performance cleaning and disinfection results on Miele decontamination units was proved in laboratory tests to be successful in decontaminating surface-adherent prions, the pathogen behind the Creutzfeld-Jacob disease. These results have since been confirmed by further 'in vivo' experiments performed by the Institute of Neuropathology at the University of Munich. This paves the way for a declaration of efficacy according to the criteria laid down by Germany's Robert Koch Institute.
Uncompromising and perfect instrument reprocessing is the key to prevent the iatrogenic spread of vCJD. Consequently, Oxivario Plus was introduced as an intensified programme to deal with poorly soluble proteins, for example fibrinaceous or denatured proteins. Oxivario Plus operates with higher concentrations of alkaline detergents and uses hydrogen peroxide in the second cleaning stage combined with extended exposure times.
In 2006, Miele reported on the successful conclusion of 'in vitro' tests. The objective of the experiments was to determine the efficacy of the Oxivario Plus and Vario TD reprocessing methods in reducing levels of prion contamination on stainless-steel mesh. Two different detection methods were used after enrichment of residual proteins in cell culture: the Western Blot method and chemiluminescence. Prions were only detected on one of the samples – one reprocessed using the less effective Vario TD method used in CSSDs for routine disinfection. None of the samples reprocessed using OxiVario Plus showed any traces of the presence of prions. To establish the sensitivity of this method of detection, a homogenate containing prions was applied to metal grilles in a predefined dilution series and incubated. This method furnished reliable proof that the method used was able to decontaminate prions even when diluted 10,000 times. Consequently, it can be claimed that the OxiVario Plus method is able to reduce prion proteins by more than 99.99%.
Germany's Robert Koch Institute requires that 'in vivo' tests be carried out before claims to prion decontamination can be made. The recent series of tests involved involved implanting tiny metal plates previously contaminated with tissue containing prions in mice. Only the mice implanted with material previously decontaminated in the OxiVario Plus process or sterilised in steam for two hours at 134°C showed no signs of contracting the disease. On the other hand, mice implanted with metal plates reprocessed using the standard Vario TD process or with a 10-8 prion solution dilution contracted the disease and died. Work is already underway to publish the test results.