MNV (step 1). Then, after drying, the hands are kneaded in a petri dish with growth medium to determine the prevalue (i.e. the number of pathogens before disinfection) (step 2). Step 3 involves disinfecting the hands with 2 x 3 ml of 70% (v/v) ethanol as a reference for 2 x 30 seconds using a standardised rubbing method. After disinfection, the hands are kneaded again in growth medium. This allows the number of pathogens remaining on the hands after disinfection to be determined (step 4; post-value). The logarithmic reduction is then calculated from the difference between the pre-value and the post-value (step 5). To test the test product, the process starts again from the beginning. However, in step 3, the hands are disinfected with the test product instead of the reference product. A quantity of disinfectant specified by the manufacturer is then rubbed in for 30–60 seconds using the standardised rubbing method. In order to pass EN 17430, the test product must be at least as effective as the reference product. EN 17846: Sporicidal efficacy of surface disinfectants against C. difficile EN 17846 [3] also describes phase 2/step 2 test procedure. However, this standard relates to the verification of the effectiveness of surface disinfectants against the spore-forming bacterium C. difficile, which frequently causes nosocomial diarrhoea and whose spores can survive on surfaces for up to five months [4]. Figure 2 shows the test procedure: four consecutive test areas, each measuring 5 x 5 cm, are marked on a test surface. The first test area is contaminated with the test pathogen and organic load (protein and, if applicable, blood) (step 1). The four test areas are then disinfected with the test product and weighed down with a standard weight, starting with test area 1 (step 2). After the exposure time, which ranges from 1–30 minutes for patient-near surfaces and 1–60 minutes for patient-far surfaces, the individual test areas are sampled using moist cotton swabs to recover any remaining pathogens (step 3). Finally, the number of pathogens on each test area is counted and compared with the initial count (step 4). To be considered effective against C. difficile, a disinfectant must reduce the pathogen count on the first test area by four logarithmic steps, while the pathogen count on test areas 2 to 4 must not exceed 50 colony-forming units. Fig 2: Procedure for testing the sporicidal efficacy of surface disinfectants in accordance with EN 17846. Continued #1 #2 #3 #1 #2 #3 #4 #1 #2 #3 #4 EN 16615 | Carrier test (4-field-test) Phase 2 / Stufe 2: Sporicidal, with mechanic Special test pathogens are applied to the first field together with an organic load. A cloth soaked in disinfectant is attached to the underside of a standard weight. The weight is then wiped over the test fields The colonies are counted. An effective disinfectant should have inactivated a certain number of cells. KNOWLEDGE 15
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