UNE ISO 22612: 2005 - Clothing for protection against infectious agents. Test method for resistance to dry microbial penetration . Requirements of assay according to UNE-EN 13795-1: 2020. Surgical clothing and drapes. Requirements and test methods. Part 1: Surgical drapes and gowns. UNE-EN 13795-2: 2020. Surgical clothing and drapes. Requirements and test methods. Part 2: Clean air suits.
Test not accredited yet in our laboratory (in process).
Bacteria can adhere to dry organic or inorganic particles. When attached to the scales of the skin, they can go through protective clothing against infectious agents, such as surgical gowns or clean air clothing. Similarly, they can penetrate through a storage container.
This standard describes a test method as well as test equipment to determine the resistance of a material to the dry penetration of bacteria found on talc particles whose size is similar to that of the scales of human skin. During the test, the talc particles are screened through the material to be tested and spore-forming bacteria are used as marker microorganisms.
To assess resistance to penetration, samples of the material under test are fixed in a container. In each container, except one, a portion of Bacillus atrophaeus-contaminated talc is poured over the sample of the material tested, leaving a container with uncontaminated sample for control. A settling plate is inserted into the base of each test or control vessel at a short distance. The apparatus on which the containers rest is vibrated using a pneumatic ball vibrator. Talc that can penetrate through the material under test is captured on the sedimentation plate. The sedimentation plates are removed and incubated to count the number of colonies obtained, which will correspond to those that have been able to penetrate through the material under test.
According to the test requirements specified in the UNE-EN 13795-1 and 13795-2 Standards, for surgical drapes, surgical gowns and clean air suits, the test must be carried out with 108 CFU/g of talc and the vibration time it should be 30 minutes. There is a limit of ≤ 300 CFU for surgical drapes and gowns in the least critical areas (in both standard and superior performance materials), ≤ 100 CFU for standard performance clean air suits and a limit of ≤ 50 CFU for superior performance clean air suits.
Standard performance materials are those that meet the minimum requirements for resistance to dry penetration, while higher performance materials correspond to those that have high requirements, since they are used, for example, in surgical procedures where a high fluid exposure, higher mechanical action, or longer surgical procedures.
For surgical cloths and gowns, according to the UNE-EN 13795-1 standard, it is only mandatory to test the least critical areas of the product (and not the critical ones), that is, the areas with the least probability of contributing to the transfer of infectious agents to and from the wound. This is because, in critical areas of the product, such as the front and sleeves of surgical gowns or parts of the drapes adjacent to surgical wounds, other requirements must be met, such as wet microbial penetration, which are also supposed to ensure resistance against dry penetration.
To carry out the test, 12 samples of 200 mm x 200 mm (20 x 20 cm) cut from the evaluated material are used (10 for the test and 2 control pieces), which are sterilized according to the manufacturer´s recommendations, and then conditioned and they are tested at a temperature of (20 ± 2)ºC and a relative humidity of (65 ± 5)%. If both sides of the material are different, the side to be exposed in the test will be the side intended to cover the source of contamination during medical use, for example, the inside side of a surgical gown or clean suit, or the patient or equipment side of a surgical cloth.
According to the UNE-EN 13795-1 and -2 standards, for each test product, the procedure should be repeated with 10 samples, calculating the arithmetic mean for the 10 valid results. The UNE-EN 13795-1 and 13795-2 standards require the calculation of the average and the lower or upper quartile to determine if a sample meets the requirements of the indicated benefits.