A European standard “EN 17422 Chemical disinfectants and antiseptics - Quantitative surface test for the evaluation of udder disinfectants used in veterinary medicine - Test method and requirements (phase 2 step 2)” describes a test method and minimum requirements for the bactericidal activity of udder disinfectants (or in the case of ready-to-use products) that form a homogeneous, physically stable preparation when diluted with hard water.
This method is applicable to udder disinfectants used in the veterinary field as pre-milking or post-milking udder disinfectants on the udder skin without mechanical effect.
The described method aims to determine the activity of commercial formulations under the conditions in which they are used. This method corresponds to a phase 2 step 2 test.
The product shall show a reduction of at least 10,0 decimal log (lg) (post-milking disinfectant) or 3,0 decimal log (lg) (pre-milking disinfectant) from the water control when tested under simulated contamination in accordance with this standard (4 g/l milk powder for post-milking udder disinfectants, 3 g/l bovine albumin for pre-milking udder disinfectants).
When performing the test, a bacterial test suspension mixed with the principally mixed substance is inoculated onto a synthetic leather test surface and kept at 30 degrees for a period of time. After this conditioning period, the test surface is immersed in the product or diluted forms of the product at 30 degrees for a specified period of time specified in the table given in the standard. At the end of this contact period, a neutralizer is added to immediately neutralize the effect of the disinfectant. Bacteria are removed from the surface by ultrasonic treatment. The number of surviving bacteria that can be recovered from the surface is determined quantitatively. The number of bacteria on a surface treated with water instead of disinfectant is also determined and the reduction is calculated.
Bactericidal activity is evaluated using the following strains as test organisms:
References to strains from other culture collections are included in the standard appendix (Appendix A). The required incubation temperature for these test organisms is 36 degrees plus/minus 1 degree or 37 degrees plus/minus 1 degree.
All weights of chemicals given in this method refer to the anhydrous salts. Alternatively, hydrated forms may be used, but the required weights must be adjusted to allow for differences in the resulting molecular weights.
Reagents should be of analytical grade or suitable for microbiological purposes. They should be free from substances that are toxic or inhibitory to the test organisms.
To increase reproducibility, it is recommended to use commercially available dehydrated material for the preparation of culture media. The manufacturer's instructions for the preparation of these products should be followed carefully.
A ready-to-use medium can be used if it meets the required specification.
A time limit for use should be established for each culture medium and reagent.
The water should be fresh distilled water and not demineralized water. If distilled water of sufficient quality is not available, water for injection may be used. The water is sterilized in an autoclave. If the water is used, for example, for the preparation and subsequent sterilization of culture media, sterilization is not necessary.
All glassware and instrument parts that will come into contact with culture media and reagents or specimen, except those provided sterile, are sterilized by one of the following methods:
Among the numerous tests, measurements, analyses and evaluation studies that our organization has carried out for businesses in various sectors, our organization also provides testing services defined in the standard “EN 17422 Chemical disinfectants and antiseptics - Quantitative surface testing for the evaluation of udder disinfectants used in veterinary medicine - Test method and requirements (phase 2 step 2)” with its trained and expert staff and advanced technological equipment.
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