• Point-of-use and inline water filters in endoscopy

    Safety for the hygienic reprocessing of endoscopes

    Medical professionals entrusted with the reprocessing of endoscopes in clinics and surgeries are aware of the challenges involved in the proper hygienic cleaning of medical devices.

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    Due to their complex design, the very narrow channels are difficult to access and the crevices and coils are susceptible to biofilm formation. If cleaning is not thorough enough, then endoscopes provide an ideal living environment for pathogens such as bacteria, viruses and fungi.

    Even though most microorganisms originating from contaminated water systems do not pose a risk of illness for healthy people, certain species can still cause serious illnesses. These include, for example, legionella, pseudomonads and mycobacteria.

    Therefore, the hygienic reprocessing of endoscopes should always be carried out in accordance with DIN EN ISO 15883 and the recommendation for the reprocessing of flexible endoscopes from the Commission for Hospital Hygiene and Infection Prevention (KRINKO).

    They also include the requirements for water quality. In order to ensure that the fresh water to be drawn for each device meets the specified requirements and is free from pathogenic microorganisms, it must be appropriately treated and have the lowest possible bacterial load.

    Increasing discussions about multi-resistant germs reinforce the growing requirements in endoscopy and place the reprocessing of medical endoscopes at the center of clinical quality management.

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    Legal requirements for the hygienic reprocessing of endoscopes

    Professional endoscope reprocessing is regulated both directly and indirectly by a number of laws, standards and recommendations and is subject to high quality requirements. On the one hand, general federal laws apply, such as the German Infection Protection Act [IfSG] and the German Medical Device Law Implementation Act [MPDG]; on the other hand, there are also special guidelines for the hygienic reprocessing of endoscopes.

    Thus, for example, the KRINKO issued a recommendation regarding “Hygiene requirements for the reprocessing of flexible endoscopes and additional endoscopic instruments”. In addition to the use of and compliance with validated processes for the reprocessing of medical devices, it also provides information on the limit values for microorganisms in order to prevent the transmission of diseases through reprocessed endoscopes.

    Further relevant links

    Hygiene requirements for the reprocessing of medical devices

    Annex 8: Hygiene requirements for the reprocessing of thermolabile endoscopes (Revised Annex 8 of the KRINKO-BfArM recommendation, 2024)

    KRINKO recommendations

    • any reprocessing shall be carried out by trained personnel in a room specially equipped for this purpose;
    • automated reprocessing in a washer-disinfector for endoscopes (WD-E) shall be preferable;
    • cleaning is carried out according to the following process steps: pre-cleaning, leak test, manual cleaning, rinsing of the cleaning solution, disinfection, final rinsing, drying and storage, documentation;
    • fresh water of microbiological drinking water quality and free of pathogenic microorganisms (pseudomonads, atypical mycobacteria, legionella) shall be used for the final rinse – tap water or non-sterile distilled water shall not suffice;
    • any suspicion of a water-borne infection must be investigated.

    Process steps in the reprocessing of endoscopes

    The KRINKO provides clear instructions for the medical-hygienic reprocessing of endoscopes. The cleaning process can be carried out manually, semi-automatically or mechanically using a washer-disinfector for flexible endoscopes (WD-E).

    • The first step of endoscope reprocessing is carried out manually immediately after the examination. Coarse impurities are removed.

    • In the reprocessing area the endoscope channels are manually cleaned using suitable brushes. The leak test is carried out in the same process step.

    • Intermediate rinsing with tap water can be carried out manually or mechanically and serves to prepare for successful disinfection. Water filtration of tap water is already recommended for this process step in order to prevent contamination of the medical device.

    • All of the channels of the endoscope are rinsed in the washer-disinfector with disinfectant solutions free of air bubbles. Only solutions with proven antibacterial, antiviral and fungicidal efficacy should be used for this purpose.

    • In order to ensure that no new germs enter the medical device after rinsing out the disinfectant solution and to prevent biofilm formation in the endoscope, the final rinse must be carried out with microbiologically safe water of drinking water quality that is free from facultative pathogenic microorganisms (category IB).

      According to the standard DIN EN ISO 15883-4, the bacterial load shall not exceed 10 CFU/100 ml. The rinse water must be free of Legionella, Pseudomonas aeruginosa and mycobacteria in 100 ml. The KRINKO recommends the use of disposable water filters in order to produce sufficient quantities of rinse water.

    • The channel systems in the endoscope are thoroughly flushed with compressed air in order to ensure the most complete drying possible.

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    Hygienic-microbiological examination

    after endoscope reprocessing
    Microbiological testing (sampling and culture) should be carried out as standard in order to prevent the transmission of infectious agents in endoscopy and to check whether there is still any contamination after reprocessing.

    For this purpose, samples are taken from the endoscope and cultivated. This makes it possible to determine whether any contamination is present. Such test procedures are commonplace in many countries, but different methods make it difficult to compare data in order to gain insights into the effectiveness of reprocessing and establish a standardized procedure.

    Contamination pathways
    Opportunistic bacterial pathogens
    Infection prevention – successful and sustainabl

    Disposable water filter as a protective barrier

    against contamination risks

    Even if the water quality is perfect, it is advisable to take protective measures to prevent infection.

    Both the Commission on Hospital Hygiene and Infection Protection and the manufacturers of endoscopes stipulate microbiologically safe rinsing water.

    The i3 ONE disposable water filter is installed directly on the tap for filling for manual pre-rinsing in the water basin. The compact Point-of-Use water filter is used to prevent infections caused by waterborne pathogens and thus supports the water quality requirements of the Robert Koch Institute with regard to endoscope reprocessing.

    When it comes to manual or semi-automatic intermediate rinsing, the i3 FOUR inline filter offers reliable protection against contamination by, for example, Legionella pneumophila, Pseudomonas aeruginosa or non-tuberculous mycobacteria (NTM). It is installed upstream of the cleaning gun for water filtration of tap water.

    In the case of automated reprocessing in the washer-disinfector, the final rinse must be carried out using demineralized water in order to prevent the entry of particles from the mains supply.

    Reverse osmosis systems and ion exchangers are usually found in central water treatment systems and supply the washer-disinfectors with demineralized water. Although this process removes all of the microorganisms from the water, the demineralized water that arrives at the washer-disinfector is often not germ-free.

    This is due to improper maintenance and servicing of the systems. The demineralized water used for the final rinse should therefore also be installed with the i3 FIVE inline filter as this acts as a reliable barrier against all waterborne germs during the intermediate and final rinses.

    The use of water filters in the various process steps of reprocessing medical endoscopes can be essential when it comes to achieving a safe reprocessing result along with optimum protection against contamination.

    New regulations are required:

    Mastering challenges, minimizing risks
    In this context we advocate revision and tightening of the requirements for the reprocessing of medical endoscopes in order to ensure safe, hygienic and largely standardized handling of these highly sensitive devices. Advanced normative foundations must be created and generally applicable regulations developed.

    Manufacturers of endoscopes should have to deal with these in equal measure. This is the only way to promote the standardization of basic user instructions in the instructions for use. This will have a positive effect on the daily challenges faced by users when handling different types of endoscopes.

    At present, the sometimes immense differences between the various manufacturers’ specifications result in unnecessarily time-consuming detailed work, increased costs for training, uncertainty and increased potential for human error.