SIST EN 14561:2006

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Chemische Desinfektionsmittel und Antiseptika - Quantitativer Keimträgerversuch zur Prüfung der bakteriziden Wirkung für Instrumente im humanmedizinischen Bereich - Prüfverfahren und Anforderungen (Phase 2, Stufe 2)Désinfectants chimiques et antiseptiques - Essai quantitatif de porte germe pour l'évaluation de l'activité bactéricide pour instruments utilisés en médecine humaine - Méthode d'essai et prescriptions (phase 2, étape 2)Chemical disinfectants and antiseptics - Quantitative carrier test for the evaluation of bactericidal activity for instruments used in the medical area - Test method and requirements (phase 2, step 2)11.080.20Dezinfektanti in antiseptikiDisinfectants and antisepticsICS:Ta slovenski standard je istoveten z:EN 14561:2006SIST EN 14561:2006en,fr,de01-september-2006SIST EN 14561:2006SLOVENSKI
STANDARD



SIST EN 14561:2006



EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14561May 2006ICS 11.080.20 English VersionChemical disinfectants and antiseptics - Quantitative carrier testfor the evaluation of bactericidal activity for instruments used inthe medical area - Test method and requirements (phase 2, step2)Désinfectants et antiseptiques chimiques - Essai quantitatifde porte germe pour l'évaluation de l'activité bactéricidepour instruments utilisés en médecine humaine - Méthoded'essai et prescriptions (phase 2, étape 2)Chemische Desinfektionsmittel und Antiseptika -Quantitativer Keimträgerversuch zur Prüfung derbakteriziden Wirkung für Instrumente imhumanmedizinischen Bereich - Prüfverfahren undAnforderungen (Phase 2, Stufe 2)This European Standard was approved by CEN on 29 August 2005.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14561:2006: ESIST EN 14561:2006



EN 14561:2006 (E) 2 Contents page Foreword.3 Introduction.4 1 Scope.5 2 Normative references.5 3 Terms and definitions.5 4 Requirements.6 5 Test method.6 5.1 Principle.6 5.2 Materials and reagents.6 5.3 Apparatus and glassware.9 5.4 Preparation of test organism suspensions and product test solutions.11 5.5 Procedure for assessing the bactericidal activity of the product.13 5.6 Experimental data and calculation.16 5.7 Verification of methodology.22 5.8 Expression of results and precision.22 5.9 Interpretation of results – conclusion.23 5.10 Test report.24 Annex A (informative)
Referenced strains in national collections.26 Annex B (informative)
Suitable neutralizers.27 Annex C (informative)
Graphical representations of the test method.29 Annex D (informative)
Example of a typical test report.31 Annex E (informative)
Information on the application and interpretation of European Standards on chemical disinfectants and antiseptics.34 Annex ZA (informative)
Relationship between this European Standard and the Essential Requirements of EU Directive 93/42/EEC.36 Bibliography.37
SIST EN 14561:2006



EN 14561:2006 (E) 3 Foreword This European Standard (EN 14561:2006) has been prepared by Technical Committee CEN/TC 216 “Chemical disinfectants and antiseptics”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2006, and conflicting national standards shall be withdrawn at the latest by November 2006. Other methods to evaluate the efficacy of chemical disinfectants and antiseptics for different applications in the medical field are in preparation. A collaborative trial will be undertaken to provide a precision annex to this standard. This European Standard has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association and supports essential requirements of EU Directive(s). For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this standard. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. SIST EN 14561:2006



EN 14561:2006 (E) 4
Introduction This European Standard specifies a carrier test for establishing whether a chemical disinfectant for use on instruments (surgical instruments, anaesthesia material, endoscopes etc.) has a bactericidal activity in the fields described in the scope. The laboratory test closely simulates practical conditions of application including pre-drying bacteria on a carrier, contact time, temperature, test organisms and interfering substances, i.e. conditions which may influence the action of chemical disinfectants in practical situations.
The obligatory conditions are intended to cover general purposes and to allow reference between laboratories and product types. Each utilization concentration of the chemical disinfectant found by this test corresponds to defined experimental conditions. However, for some applications the recommendations of use of a product may differ and therefore additional test conditions need to be used. SIST EN 14561:2006



EN 14561:2006 (E) 5
1 Scope This European Standard specifies a test method and the minimum requirements for bactericidal activity of chemical disinfectant products that form a homogeneous, physically stable preparation when diluted with hard water – or in the case of ready-to-use products – with water.
This European Standard applies to products that are used in the medical area for disinfecting instruments by immersion – even if they are not covered by the EEC/93/42 Directive on Medical Devices. This European Standard applies to areas and situations where disinfection is medically indicated. Such indications occur in patient care, for example:  in hospitals, in community medical facilities and in dental institutions;  in clinics of schools, of kindergardens and of nursing homes;  and may occur in the workplace and in the home. It may also include services such as laundries and kitchens supplying products directly for the patients. NOTE This method corresponds to a phase 2, step 2 test (see Annex E). 2 Normative references The following referenced documents are indispensable for the application of this European Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 12353, Chemical disinfectants and antiseptics – Preservation of test organisms used for the determination of bactericidal, sporicidal and fungicidal activity 3 Terms and definitions For the purposes of this European Standard, the following terms and definitions apply. 3.1 product chemical agent or formulation used as a chemical disinfectant or antiseptic 3.2 bactericide product that kills vegetative bacteria under defined conditions NOTE The adjective derived from "bactericide" is "bactericidal". 3.3 bactericidal activity capability of a product to produce a reduction in the number of viable bacterial cells of relevant test organisms under defined conditions 3.4 clean conditions conditions representative of surfaces which have been cleaned satisfactorily and/or are known to contain minimal levels of organic and/or inorganic substances SIST EN 14561:2006



EN 14561:2006 (E) 6 3.5 dirty conditions conditions representative of surfaces which are known to or may contain organic and/or inorganic substances 4 Requirements The product, when diluted with hard water or – in the case of ready-to-use products – with water, and tested in accordance with Clause 5 under simulated clean conditions (0,3 g/l bovine albumin solution) or simulated dirty conditions (3 g/l bovine albumin solution, plus 3 ml/l washed sheep erythrocytes) according to its practical applications and under the obligatory test conditions (three selected test organisms, 20 °C, 60 min), shall demonstrate at least a decimal log (lg) reduction in counts of 5. The bactericidal activity shall be evaluated using the following three test organisms: Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus hirae. Where indicated, additional specific bactericidal activity shall be determined applying other contact times, temperatures, test organisms and interfering substances (5.5.1.1) in order to take into account intended specific use conditions.
NOTE For these additional conditions, the concentration defined as a result can be lower than the one obtained under the obligatory test conditions.
5 Test method 5.1 Principle 5.1.1 A test suspension of bacteria in a solution of interfering substances is spread on a glass carrier. After drying the carrier is immersed into a sample of the product as delivered and/or diluted with hard water (for ready to use products: water). The carrier is maintained at 20 °C ± 1 °C for 60 min ± 10 s (obligatory test conditions). At the end of this contact time, the carrier is transferred into a neutralizer containing glass beads. The bacteria are to be severed from the surface by shaking. The numbers of surviving bacteria in each sample are determined and the reduction is calculated. 5.1.2 The test is performed using Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus hirae as test-organisms (obligatory test conditions). 5.1.3 Additional and optional contact times and temperatures are specified. Additional interfering substances can be used. 5.2 Materials and reagents 5.2.1 Test organisms The bactericidal activity shall be evaluated using the following strains as test organisms1):  Pseudomonas aeruginosa ATCC
15442  Staphylococcus aureus ATCC
6538  Enterococcus hirae ATCC
10541
1) The ATCC numbers are the collection numbers of strains supplied by the American Type Culture Collections (ATCC). This information is given for the convenience of users of this European Standard and does not constitute an endorsement by CEN of the product named. SIST EN 14561:2006



EN 14561:2006 (E) 7 NOTE See Annex A for strain references in some other culture collections. The required incubation temperature for these test organisms is 36 ° ± 1 °C or 37 °C
±
1 ° (5.3.2.3). The same temperature (either 36 °C or 37 °) 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 All weights of chemical substances given in this European 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.
NOTE 1 To improve reproducibility, it is recommended that commercially available dehydrated material is used for the preparation of culture media. The manufacturer's instructions relating to the preparation of these products should be rigorously followed.
NOTE 2 For each culture medium and reagent a limitation for use should be fixed. 5.2.2.2 Water The water shall be freshly glass distilled water and not demineralized water. Sterilize in the autoclave (5.3.1). NOTE 1 Sterilization is not necessary if the water is used – e.g. for preparation of culture media – and subsequently sterilized. NOTE 2 If distilled water of adequate quality is not available, water for injections (see bibliographic reference [1]) can be used. NOTE 3 See 5.2.2.7 for the procedure to prepare hard water. 5.2.2.3 Tryptone Soya Agar (TSA)  Tryptone, pancreatic digest of casein 15,0 g  Soya peptone, papaic digest of Soybean meal 5,0 g  Sodium Chloride (NaCl) 5,0 g  Agar 15,0 g  Water (5.2.2.2) to 1 000,0 mlSterilize in the autoclave (5.3.1). After sterilization the pH of the medium shall be equivalent to 7,2 ± 0,2 when measured at (20 ± 1)°C (5.3.2.4). SIST EN 14561:2006



EN 14561:2006 (E) 8 NOTE In special circumstances (problems with neutralization – see 5.5.1.2 and 5.5.1.3) it may be necessary to add neutralizer to TSA (see B.3). 5.2.2.4 Diluent Tryptone Sodium Chloride Solution:  Tryptone, pancreatic digest of casein
1,0 g  Sodium chloride (NaCl)
8,5 g  Water (5.2.2.2)
to 1 000,0 ml Sterilize in the autoclave (5.3.1). After sterilization the pH of the diluent shall be equivalent to 7,0 ± 0,2 when measured at (20 ± 1)°C. 5.2.2.5 Neutralizer The neutralizer shall be validated for the product being tested in accordance with 5.5.1 and 5.5.2. The neutralizer shall be sterile. NOTE Information on neutralizers that have been found to be suitable for some categories of products is given in B.2. 5.2.2.6 Sterile defibrinated sheep blood From a commercial supplier or prepared according to EN 14820. 5.2.2.7 Hard water for dilution of products Prepare:  Solution A: Dissolve 19,84 g anhydrous magnesium chloride (MgCl2) or an equivalent of hydrated magnesium chloride and 46,24 g anhydrous calcium chloride (CaCl2) or an equivalent of hydrated calcium chloride in water (5.2.2.2) and dilute to 1 000 ml. Sterilize in the autoclave (5.3.1). Store the solution in a refrigerator (5.3.2.8) for no longer than one month.  Solution B: Dissolve 35,02 g sodium bicarbonate (NaHCO3) in water (5.2.2.2) and dilute to 1 000 ml. Sterilize by membrane filtration (5.3.2.7). Store the solution in a refrigerator (5.3.2.8) for no longer than one week.  Hard water: For the preparation of 1 l, place 600 ml to 700 ml water (5.2.2.2) in a 1 000 ml volumetric flask (5.3.2.12) and add 6,0 ml of solution A, then 8,0 ml of solution B. Mix and dilute to 1 000 ml with water (5.2.2.2). The pH of the hard water shall be 7,0 ± 0,2 when measured at (20 ± 1) °C. If necessary adjust the pH by using a solution of approximately 40 g/l (about 1 mol/l) of sodium hydroxide (NaOH) or approximately 36,5 g/l (about 1 mol/l) of hydrochloric acid (HCl). The hard water shall be freshly prepared under aseptic conditions and used within 12 h. NOTE When preparing the product test solutions (5.4.2) the addition of the product to this hard water produces a different final water hardness in each test tube. In any case the final hardness is lower than 300 mg/l of calcium carbonate (CaCO3) in the test tube. 5.2.2.8 Interfering substances 5.2.2.8.1 General The interfering substance shall be chosen according to the conditions of use laid down for the product.
SIST EN 14561:2006



EN 14561:2006 (E) 9 The interfering substance shall be sterile and prepared at 10 times its final concentration in the test. The ionic composition (e.g. pH, calcium and/or magnesium hardness) and chemical composition (e.g. mineral substances, protein, carbohydrates, lipids, detergents) shall be defined.
NOTE In the following, the term “interfering substance” is used even if it contains more than one substance. 5.2.2.8.2 Clean conditions (bovine albumin solution – low concentration)  Dissolve 0,30 g of bovine albumin fraction V (suitable for microbiological purposes) in 100 ml of diluent (5.2.2.4).
 Sterilize by membrane filtration (5.3.2.7), keep in a refrigerator (5.3.2.8) and use within 1 month.  The final concentration of the bovine albumin in the test procedure (5.5) is 0,3 g/l. 5.2.2.8.3 Dirty conditions (Mixture of bovine albumin solutions – high concentration with sheep erythrocytes (see 5.2.2.6)) Dissolve 3,00 g of bovine albumin fraction V (suitable for microbiological purposes) in 97 ml of diluent (5.2.2.4). Sterilize by membrane filtration (5.3.2.7). Prepare at least 8,0 ml fresh sterile defibrinated sheep blood (5.2.2.6). Centrifuge the sheep blood at 800 gN for 10 min. After discarding the supernatant, resuspend erythrocytes in diluent (5.2.2.4). Repeat this procedure at least 3 times, until the supernatant is colourless. Resuspend 3 ml of the packed sheep erythrocytes in the 97 ml of sterilized bovine albumin solution (see above). To avoid contamination this mixture should be split in portions probably needed per day and kept in separate containers for a maximum of 7 days in a refrigerator at 2° C to 8° C. The final concentration of bovine albumin and sheep erythrocytes in the test procedure (5.5) shall be 3 g/l and 3 ml/l respectively. 5.3 Apparatus and glassware 5.3.1 General Sterilize all glassware and parts of the apparatus that will come into contact with the culture media and reagents or the sample, except those which are supplied sterile, by one of the following methods: a) by moist heat, in the autoclave [5.3.2.1 a)] ; b) by dry heat, in the hot air oven [5.3.2.1 b)]. 5.3.2 Usual microbiological laboratory equipment2)
and in particular, the following: 5.3.2.1 Apparatus for sterilization: a) for moist heat sterilization, an autoclave capable of being maintained at ()C12130°+ for a minimum holding time of 15 min;
2) Disposable sterile equipment is an acceptable alternative to reusable glassware. SIST EN 14561:2006



EN 14561:2006 (E) 10 b) for dry heat sterilization, a hot air oven capable of being maintained at (1805 0
+) °C for a minimum holding time of 30 min, at (1705 0
+) °C for a minimum holding time of 1 h or at (1605 0
+) °C for a minimum holding time of 2 h. 5.3.2.2 Water baths, capable of being controlled at 20° C ± 1 °C, at 45 °C ± 1 °C (if pour plate technique is used – see 5.5.1.7) and at additional test temperatures ± 1 °C (5.5.1). 5.3.2.3 Incubator, capable of being controlled at either 36 °C ± 1 °C or at 37 °C ± 1 °C. The same temperature shall be used for all incubations performed during a test and its controls and validation.
5.3.2.4 pH-meter, having an inaccuracy of calibration of no more than ± 0,1 pH units at (20 ± 1)°C NOTE For measuring the pH of the agar-media (5.2.2.3) a puncture electrode or a flat membrane electrode should be used. 5.3.2.5 Stopwatch 5.3.2.6 Shakers a) Electromechanical agitator, e.g. Vortex® mixer3). b) Mechanical shaker 5.3.2.7 Membrane filtration apparatus, constructed of a material compatible with the substances to be filtered, with a filter holder of at least 50 ml volume, and suitable for use of filters of diameter 47 mm to 50 mm and 0,45 µm pore size for sterilization of hard water (5.2.2.7) and bovine albumin (5.2.2.8). The vacuum source used shall give an even filtration flow rate. In order to obtain an uniform distribution of the microorganisms over the membrane and in order to prevent overlong filtration, the device shall be set so as to obtain the filtration of 100 ml of rinsing liquid in 20 s to 40 s. 5.3.2.8 Refrigerator, capable of being controlled at 2 °C to 8 °C. 5.3.2.9 Graduated pipettes of nominal capacities 10 ml and 1 ml and 0,1 ml. Calibrated automatic pipettes may be used. 5.3.2.10 Petri dishes (plates) of size 90 mm to 100 mm. 5.3.2.11 Glass beads (Diameter: 3 mm to 4 mm). 5.3.2.12 Volumetric flasks. 5.3.2.13 Glass beads (diameter: 0,25 mm to 0,5 mm) 5.3.2.14 Centrifuge (800 gN).
5.3.2.15 Cylindrical plastic screw cap tubes, contents of about 15 ml, diameter about 18 mm (for the carrier). 5.3.2.16 Loop (metal or plastic). 5.3.2.17 Frosted glass carriers, 15 mm x 60 mm x 1 mm, one surface sandblasted. For preparation the glass carrier is boiled 10 min in a suitable detergent, cleaned minimum 3 times with water (5.2.2.2) and at the
3) Vortex® in an example of a suitable product available commercially. This information is given for the convenience of users of this European Standard and does not constitute an endorsement by CEN of this product. SIST EN 14561:2006



EN 14561:2006 (E) 11 end once with ethanol (70 Volume %). Mark a square (lateral length: 10 mm) at one end of the dried carrier on its sandblasted surface, about 2 mm off the three edges. Sterilize in the heat oven [5.3.1b)]. After the sterilization process the markings of the “inoculation square” shall be clearly visible.
Key 1 Inoculation square Figure 1 — Frosted glass carrier with markings
5.4 Preparation of test organism suspensions and product test solutions 5.4.1 Test organism suspensions (Test and validation suspension) 5.4.1.1 General For each test organism two different suspensions have to be prepared: the “test suspension” to perform the test and the “validation suspension” to perform the controls and method validation. 5.4.1.2 Preservation and stock cultures of test organisms The test organisms and their stock cultures shall be prepared and kept in accordance with EN 12353. 5.4.1.3 Working culture of test organisms In order to prepare the working culture of test organisms (5.2.1), subculture from the stock culture (5.4.1.2) by streaking onto TSA (5.2.2.3) slopes or plates and incubate (5.3.2.3). After 18 h to 24 h prepare a second subculture from the first subculture in the same way and incubate for 18 h to 24 h. From this second subculture, a third subculture may be produced in the same way. The second and/or the third subculture are the working culture(s). If it is not possible to prepare the second subculture on a particular day, a 48 h subculture may be used for subsequent subculturing, provided that the subculture has been kept in the incubator (5.3.2.3) during the 48 h period.
Never produce and use a fourth subculture. 5.4.1.4 Test suspension a) Take 10 ml of diluent (5.2.2.4) and place in a 100 ml flask with 5 g of glass beads (5.3.2.11). Take the working culture (5.4.1.2) and transfer loopfuls (5.3.2.16) of the cells into the diluent (5.2.2.4). The cells should be suspended in the diluent by rubbing the loop against the wet wall of the flask to dislodge the SIST EN 14561:2006



EN 14561:2006 (E) 12 cells before immersing in the diluent. Shake the flask for 3 min using a mechanical shaker [5.3.2.6b)]. Aspirate the suspension from the glass beads and transfer to a tube.
b) Adjust the number of cells in the suspension to 1,5 x 109 cfu/ml4) to 5,0 x 109 cfu/ml using the diluent, estimating the numbers of units by any suitable means. Maintain this test suspension in the water bath at 20 °C
and use within 2 h. Adjust the temperature according to 5.5.1.1a) and 5.5.1.4 only immediately before the start of the test. NOTE The use of a spectrophotometer for adjusting the number of cells is highly recommended (about 620 nm wavelength – cuvette 10 mm path length). Each laboratory should therefore produce a calibration curve for each test organism, knowing that suitable values of optical density are generally found between 0,150 and 0,460. To achieve reproducible results of this measurement it may be necessary to dilute the test suspension, e.g. 1+9. A colorimeter is a suitable alternative. c) For counting prepare 10-7 and 10-8 dilutions of the test suspension using diluent (5.2.2.4). Mix [5.3.2.6a)].
d) Take a sample of 1,0 ml of each dilution in duplicate and inoculate using the pour plate or the spread plate technique.
1) When using the pour plate technique, transfer about half of each 1 ml sample into separate Petri dishes (i.e. in duplicate = four plates) and add 15 ml to 20 ml melted TSA (5.2.2.3), cooled to 45 °C ± 1 °C.
2) When using the spread plate technique spread each 1,0 ml sample – divided in portions of approximately equal size – on an appropriate number (at least two) of surface dried plates containing TSA (5.2.2.3). For incubation and counting see 5.4.1.6. 5.4.1.5 Validation suspension a) To prepare the validation suspension, dilute the test suspension (5.4.1.3) with the diluent (5.2.2.4) to obtain 3,0 x 102 cfu/ml to 1,6 x 103 cfu/ml (about one fourth (1+3) of the 10-6 dilution). b) For counting prepare a 10-1 dilution with the diluent (5.2.2.4). Mix [5.3.2.6a)]. Take a sample of 1,0 ml in duplicate and inoculate using the pour plate or the spread plate technique [5.4.1.3 d1) or d2)]. For incubation and counting see 5.4.1.6. 5.4.1.6 Incubation and counting of the test and the validation suspensions a) Incubate (5.3.2.3) the plates for 20 h to 24 h. Discard any plates which are not countable (for any reason). Count the plates and determine the number of colony forming units. Incubate the plates for a further 20 h to 24 h. Do not recount plates which no longer show well separated colonies. Recount the remaining plates. If the number has increased use only the higher number for further evaluation. b) Note for each plate the exact number of colonies but record > 330 for any counts higher than 330 and determine the VC-values according to 5.6.2.2.
c) Calculate the numbers of cfu/ml in the test suspension N and in the validation suspension NV using the method given in 5.6.2.3 and 5.6.2.5. Verify according to 5.7.
4) cfu/ml = colony forming unit per millilitre. SIST EN 14561:2006



EN 14561:2006 (E) 13 5.4.2 Product test solution Product test solutions shall be prepared in hard water (5.2.2.7) at minimum three different concentrations to include one concentration in the active range and one concentration in the non-active range. The product as received may be used as one of the product test solutions.
Dilutions of ready-to-use products, i.e. products which are not diluted when applied, shall be prepared in water (5.2.2.2) instead of hard water. For solid products, dissolve the product as received by weighing at least 1 g ± 10 mg of the product in a volumetric flask and filling up with hard water (5.2.2.7). Subsequent dilutions (i.e. lower concentrations) shall be prepared in volumetric flasks (5.3.2.12) on a volume/volume basis in hard water (5.2.2.7).
For liquid products, dilutions of the product shall be prepared with hard water on a volume/volume
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