EN 13623:2010 – Chemical disinfectants and antiseptics — Quantitative suspension test for the evaluation of bactericidal activity against Legionella of chemical disinfectants for aqueous systems — Test method and requirements (phase 2, step 1)

5 Test methods
5.1 Principle
5.1.1 A sample of the product diluted with hard water (5.2.2.7 or 5.2.2.10) is added to a test suspension of bacteria in a solution of an interfering substance. The mixture is maintained at either (20 ± 1) °C or (30 ± 1) °C for 60 min ± 10 s or (15 ± 1) h (obligatory test conditions). At the end of the chosen contact time, an aliquot is taken, and the bactericidal and/or the bacteriostatic activity in this portion is immediately neutralized or suppressed by a validated method. The method of choice is dilution-neutralization.
If a suitable neutralizer cannot be found membrane filtration is used. The numbers of surviving bacteria in each sample are determined and the reduction is calculated.
5.1.2 The test is performed using Legionella pneumophila as test organism (obligatory test conditions). 5.1.3 Additional and optional contact times are specified. Additional test organisms may be used.
5.2 Materials and reagents
5.2.1 Test organism The bactericidal activity shall be evaluated using the following strain as test organism 1 ) : Legionella pneumophila: serogroup 1, Philadelphia (NCTC 11192; ATCC 33152). If required for specific applications, additional test organisms may be used, e.g. Legionella pneumophila serogroup 1 Benidorm (NCTC 12006, ATCC 43108).
The required incubation temperature for this test organism is (36 ± 1) °C or (37 ± 1) °C (5.3.2.3). The same temperature (either 36 °C or 37 °C) shall be used for all incubations performed during a test and its control and validation. If additional test organisms are used, they shall be incubated under optimum growth conditions (temperature, time, atmosphere, media) noted in the test report. If the additional test organisms selected do not correspond to the specified strains, their suitability for supplying the required inocula shall be verified. If these additional test organisms are not classified at a reference centre, their identification characteristics shall be stated. In addition, they shall be held by the testing laboratory or national culture collection under a reference for five years.
5.2.2 Culture media and reagents
5.2.2.1 General Unless specifically stated, all weights of chemical substances given in this standard refer to the anhydrous salts. Hydrated forms may be used as an alternative, but the weights required shall be adjusted to allow for consequent molecular weight differences. The reagents shall be of analytical grade and/or appropriate for microbiological purposes. They shall be free from substances that are toxic or inhibitory to the test organisms.
EN 13623:2010 – Chemical disinfectants and antiseptics — Quantitative suspension test for the evaluation of bactericidal activity against Legionella of chemical disinfectants for aqueous systems — Test method and requirements (phase 2, step 1)