Viral bioindicator laundering process tested for virucidal efficacy
In May 2009, the Institute for Hygiene and Biotechnology (IHB) at the Hohenstein Institute first introduced a new way to test disinfectant laundering processes for their virucidal efficacy by using a viral bioindicator based on the bacteriophage MS2. Through further modification of this testing method and trials carried out using a commercial, conventional process listed by the RKI at a laundry, the researchers at Hohenstein have successfully proven that viral bioindicators can be used to assess objectively the virucidal efficacy of disinfectant laundering processes not only in simulated laundering processes, but also under actual, field conditions. Starting now, this new testing method allows the IHB at the Hohenstein Institute to offer an effective quality assurance tool for the detergent industry and laundering operations. Beyond that, in view of the increasing number of cases of viral illness, an important, additional tool has also been made available for preventive health care.
The viral bioindicator is, therefore, a novelty in the area of applied hygiene. Due to the lack of a suitable testing method, there have been until today no criteria for monitoring anti-viral (virucidal) efficacy of disinfectant laundering processes in the field. Using a method analogous to the standard techniques used by the German Association for Hygiene and Microbiology (Deutsche Gesellschaft für Hygiene und Mikrobiologie (DGHM)) to assess the bactericidal efficacy of chemical disinfectant processes, the IHB in May carried out laundering trials with test textile swatches contaminated with the bacteriophage MS2 (a pathogen similar to Norovirus). In laboratory conditions similar to those in the field, it was demonstrated that the bioindicators containing bacteriophages such as MS2 are suitable for testing and proving the virucidal efficacy of disinfectant laundering.
The Hohenstein Institute's newly developed method is even appropriate for suitability testing of disinfectant laundering processes in field conditions in accordance with the Sections 4.4.3 and 6.4 of the guidelines of the Commission for Hospital Hygiene and Applied Infection Control of the Robert Koch Institute. Upon successful completion of this special suitability test, it is incumbent upon the consultant in charge of hygiene at the IHB to recognise the disinfectant efficacy of the laundering process.
This means that in future it will be possible to use a viral bioindicator to test reprocessing of Sector B (effective against viruses) laundry in the field in a way comparable to the procedure for quality assurance currently used for bactericidal laundry (Sector A).
Laundry detergent manufacturer CHT R. Beitlich GmbH agreed to become a pilot customer and became the first to use viral bioindicators in practice. Laundering tests were carried out at the facility of Busch Textilservice GmbH & Co. KG in Bärenbach. In this field trial, bioindicators were applied in three independent, tunnel washer laundering cycles. At the same time, all process parameters were monitored, as well as sampling washwater for presence of the test virus. In experiments carried out under field conditions, CHT R. Beitlich GmbH's BEICLEAN HWA/BEIBLEACH WP35 process listed by the RKI achieved perfect results. As a result, the virucidal efficacy of the listed process could be confirmed in testing under actual field conditions.