Chemical-thermal textile disinfection - Test method and requirements (phase 2, step 2). (EN 16616: 2022 Standard)

Test accredited by ENAC (Spanish National Accreditation Entity) for its performance with the mandatory microorganisms according to the standard, for the viruses indicated by the EN 14776 standard and the microorganisms/viruses indicated by the BPR Guidance.

This standard describes a test on carrier to establish whether a disinfecting product or a combination of products for the treatment of contaminated textile fabric intended to act in a single wash shows the required microbicidal activity. The standard is intended to validate only the disinfection part of the laundry process. This laboratory test takes into account the practical conditions of application of the product, including contact time, temperature, test microorganisms and interfering substances, i.e. conditions that may influence its action in practice. Each effective dose of the chemical disinfectant found by this test corresponds only to the experimental conditions chosen. When the actual conditions differ from those specified by the standard, additional tests should be carried out to determine the effective dose. Instructions for use are the responsibility of manufacturers of the detergents or disinfectants.

In the test a washing machine with specific characteristics specified by the standard is used, which allows to specify all the washing characteristics. The supplier's instructions should be enough to allow the method described in the standard to be carried out completely (for example, dosing the disinfectant at any stage of the wash, such as rinsing or disinfection at 40°C).

This standard applies to the areas and situations for which disinfection is medically indicated. Such indications occur during patient care, for example: a) in hospitals, community medical facilities and dental institutions; b) in clinics of schools, of kinder gardens, and nursing homes; and could occur in the workplace and in the home. It could also include services such as laundries and Kitchens supplying products directly for the patients.

This is a phase 2, step 2 assay, that simulates the conditions of application of the product. It is intended to determine the activity of a product or a product combination under the conditions in which they are used.

For processes with a temperature <60°C, the process of thermochemical disinfection of a textile fabric is considered effective when in three test series (within a given time, at a recommended dosage, and at a recommended temperature and liquid index), a log reduction of 7 for bacteria; of 6 for Candida albicans and Aspergillus brasiliensis, and a logarithmic reduction of 7 for mycobacteria (Mycobacterium avium and/or Mycobacterium terrae) is obtained. This reduction shall be shown at least on 8 of 10 contaminated carriers in each series. Besides, no test organisms must be detected on the non-contaminated carriers. As a minimum requirement, bactericidal and yeasticidal activity should be assessed using the following test microorganisms: for the bactericidal activity Pseudomonas aeruginosa, Escherichia coli (K12), Staphylococcus aureus and Enterococcus hirae and for the yeasticidal activity Candida albicans. If additional fungicidal activity is claimed, Candida albicans and Aspergillus brasiliensis must be used as a test microorganism. If further tuberculocidal activity is claimed, Mycobacterium terrae should be used as the test microorganism. If a mycobactericidal effect is needed, it is necessary to test with Mycobacterium terrae and Mycobacterium avium.

For processes with temperatures ≥ 60°C, it is considered effective when a logarithmic reduction of Enterococcus faecium superior to 7, is achieved in three test series (within a given time, at a recommended dose, at a process temperature ≥ 60°C and a defined liquid index) on the inside and outside of the carrier. This reduction shall be shown at least on 8 of 10 contaminated carriers in each series. Besides, no test organisms must be detected on the non-contaminated carriers. This includes fungicidal, mycobactericidal and tuberculocidal activities. In addition to the mandatory test microorganisms, additional test microorganisms may be selected in accordance with the practical use considered for the product.

The tests use cotton fabric carriers that are contaminated with a test suspension of microorganisms in defibrinated sheep blood. After drying the carriers, they are placed in cotton towels and then subjected to the disinfection process in the washing machine at temperatures of t < 60°C or t ≥ 60°C, as chosen by the manufacturer of the product under test. Non contaminated carriers are also included in the washing machine as a control. The process refers to the disinfection step without prewash. At the end of the disinfection stage, the towels with the carriers must be removed, in which after the corresponding neutralization of the disinfectant, the microorganisms present will be counted.

The procedure described by the EN 16616 standard has been adapted in our laboratory to evaluate the virucidal activity by means of an internal procedure with the viruses indicated by the EN 14476 standard (test accredited under internal procedure based on the EN 16616 standard). EN 16616 standard does not indicate viruses as test organisms and therefore does not indicate the requirements to consider a product to have antiviral activity against. The results are indicated as the log reduction and the percentage reduction obtained for each test virus after treatment with the product. Tests at temperatures above 30ºC must be carried out with a virus resistant to temperature, murine Parvovirus.

Important note: The previous version of the EN 16616 Standard indicated the requirement to previously demonstrate that the product presents activity against the test microorganisms in a suspension test (phase 2, step 1 test) of the medical area (EN 13727, EN 13624, EN 14476 or EN 14348 standards) to the requested test concentration or a lower one, by means of a report made in an accredited laboratory. The new version eliminates this requirement but still requires controls of the test that are carried out in phase 2, step 1 tests. We recommend to consult to registration authorities if they will require to carry out these tests.

Performance of the test following the EN 16616 standard, but under specific conditions of the BPR Guidance (accredited test in our laboratory):

The ECHA BPR Guidance indicates for textile disinfection products in the PT2, PT3 and PT4 area, the test under standard EN 16616 at the time and temperature indicated by the manufacturer, according to the conditions of use. As for dirty conditions, it allows interfering substances to be adapted to the area of ​​use (clean or dirty). As test microorganisms, the BPR Guidance indicates for the PT2 area: for temperatures <40ºC, microorganisms indicated in the EN 16616 standard, for temperatures between 40ºC and 60ºC, the same microorganisms, but an additional control at 20ºC is needed to validate the organisms; dirty conditions for prewash and main wash and clean conditions for last rinse. For temperatures ≥60ºC, Enterococcus faecium. For tests with virus, test with  Adenovirus and murine Norovirus or Vaccinia virus can be performed at temperatures up to 30ºC, the procedure at temperatures above 30ºC must be performed with murine Parvovirus. For PT3 products, and temperatures <40ºC, Staphylococcus aureus, Pseudomonas aeruginosa, Enteroccocus hirae, and Proteus vulgaris; and for textiles used for teat disinfection, P. hauseri should be replaced by Escherichia coli and Streptococcus uberis (bactericidal activity); Candida albicans, Aspergillus brasiliensis (yeasticidal or fungicidal activity); Porcine Parvovirus, or in the case of teat disinfection, Vaccinia virus (virucidal activity), and Mycobacterium avium (mycobactericidal activity); clean or dirty conditions. For tests with viruses, the maximum temperature is 30ºC. Lastly, for PT4 for temperatures <40ºC: Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus hirae and Escherichia coli or only Enterococcus faecium for temperatures ≥40ºC (bactericidal activity), Candida albicans, Aspergillus brasiliensis (yeasticidal or fungicidal activity), and Adenovirus type 5 and murine Norovirus or only Murine Parvovirus for temperatures >30ºC (virucidal activity); clean or dirty conditions. The reductions to be obtained are the same as those indicated by the EN 16616 standard. The test with viruses, not included in the EN 16616 standard, is performed according to an internal procedure. The BPR guidance does not indicate a criterion to consider that the product has virucidal activity, so results are reported as the logarithmic reduction and the reduction percentage obtained for each virus.

Screening tests for textile disinfection products (test not accredited):

The screening test is not carried out in the industrial washing machine, but a laboratory-scale equipment (Gyrowash) is used that simulates the washing process. A cloth support with the test microorganism and the interfering substance will be included in each of the test containers (metal containers of 1 L capacity) with the product solution and the ballast load in the indicated proportion. It should be considered that although the test simulates the washing carried out in the industrial washing machine, the test is not completely equivalent, so this test serves as a guide, but does not guarantee that the product complies with the EN 16616 standard.