The importance and relevance of endoscope washer disinfectors (EWD’s) has increased over the years as the move from manual to automatic reprocessing continues. In the UK this occurred in 1997 with the introduction of HTM 20-30, which offered guidance on the management and decontamination of flexible endoscopes. While the choice of chemical disinfectant can vary, what links every EWD together is the requirement to produce bacteria-free rinse water.
Bacteria-free rinse water in an EWD is achieved when the bacteria Total Viable Count (TVC) is at zero. Since the introduction of a more bacteria-friendly agar and a five-day incubation period in the UK, TVC’s have rocketed. The latest UK guidelines published in 2016 “HTM 01-06: Decontamination of flexible endoscopes” detail a new quarterly Pseudomonas aeruginosa test and the increase from annual to quarterly testing for environmental mycobacteria. This will further challenge rinse water quality in an EWD. The claim to ‘bacteria-free rinse water’ will become harder to achieve as laboratory tests become mandatory and more frequent.
In the UK, there are two widely-used methods to achieving bacteria-free rinse water: filtration and Reverse Osmosis (RO). Although both methods offer advantages to producing bacteria-free rinse water, they do not come without problems, maintenance and high failure rates. Both methods require regular disinfecting with chlorine to prevent biofilm from building up and breaking into the water supply, contaminating the EWD. Once bacteria have entered an EWD, they will establish as biofilm. The only way to remove biofilm is to use high-strength chlorine in a deep-clean purge. If this fails to lower bacteria levels, pipework may need to be replaced which can be costly and carry the risk that biofilms are present somewhere else in the EWD. Once bacteria have been removed, they can establish again via contaminated filters, RO or poorly washed endoscopes.
Tristel Rinse Assure: the answer to bacteria-free rinse water
The latest UK standard “HTM 01-06: Part B – Design and Installation” includes a section on water quality and water treatment which details the requirements for rinse water such as hardness, pH, conductivity and microbiology. It also lists the common methods of rinse water treatment, including filtration and RO. A further method “disinfectant addition” is listed as an effective method for reducing biofilm formation and growth of contaminants. This is achieved by adding a chlorine-based disinfectant to the water supplying the EWD. HTM 01-06 states:
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Part B 2.27: “In some EWDs, a chlorine compound is added to the final rinse-water to prevent microbial contamination.”
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Part B 2.62: “Residual chlorine remaining in a reprocessed endoscope may reduce the possibility of biofilm formation and growth of contaminants.”
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Biofilm formation 2.82: “The addition of a non-toxic biocide to the final rinse-water may help prevent the formation of biofilm.”
Tristel Rinse Assure doses low levels of Tristel’s proprietary chlorine dioxide chemistry into the mains water used to supply an EWD’s decontamination cycle, ensuring that all water is of the highest quality and bacteria-free. The biocide is generated by mixing a Base (a citric acid solution) and Activator (a sodium chlorite solution) at point of use. Chlorine dioxide is recognised by the World Health Organisation (WHO) for the treatment of drinking water at a concentration of 0.5ppm. Chlorine dioxide is a safe and effective biocide used in many healthcare settings around the world.
Tristel Rinse Assure is effective in reducing high levels of microbiological contamination due to constant exposure of biofilm to the disinfectant. Dosage levels can be altered depending on the expected bioburden. Tristel Rinse Assure doses precisely in relation to the amount of water flowing through the mains water supply and needs of the EWD. Due to the low concentration of chlorine dioxide solution there are no issues with machine or endoscope compatibility; any type of EWD can be supplied by Tristel Rinse Assure.
Scientifically derived data demonstrates that the chlorine dioxide solution injected into the final rinse water of an EWD does not pose a toxicological risk from any possible residue left of the reprocessed endoscope. There is no interaction with other detergents and disinfectant chemistries used in EWD’s. The low level of chlorine dioxide dosed into the water supply to an endoscope washer disinfector has been proven not to affect the efficacy and chemical composition of detergents (including enzymatic) and disinfectants (including peracetic acid) commonly used in EWD’s.
Tristel Rinse Assure features an integrated track and trace system which enables the operator to constantly monitor the process via the Operator Interface Touch Screen, checking dosing levels, concentration and other parameters.
The latest Tristel Rinse Assure model contains an RO membrane as well as filtration and chemical dosing. This makes Tristel Rinse Assure the most compliant water management system compared to any other type of rinse water management system on the market. A version of Tristel Rinse Assure which does not contain RO is also available to hospitals seeking to solve high TVC problems as well as microbial contamination in an EWD.
As more hospitals begin to adopt and follow guidelines for managing rinse water, Tristel Rinse Assure is available to provide a compliant, cost-effective and superior method to filtration and RO. For more information, please visit Tristel at the IDSC exhibition or contact us.
