Evaluation of bactericidal activity of a non-porous antimicrobial surface used in a dry environment (ISO 7581: 2023 standard). 

Test not accredited yet in our laboratory. 

The ISO 7581 standard specifies a test to determine the bactericidal activity of non-porous surfaces used in a dry environment determining the reduction obtained in a bacterial inoculum deposited on the test surfaces, comparing the mean counts recovered from the test surface with those recovered from a reference surface (stainless steel disk without bactericidal activity) after a selected contact time.

In this test, reference and test surfaces and the reference surfaces are inoculated separately with the test bacteria (Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus hirae and Escherichia coli) and the inoculum is leaved to dry. After drying, the contact time starts and the surfaces are maintained at 20ºC, at a relative humidity between 30% and 65%. After drying (contact time of 0) and the contact time requested by the client (minimum 1 hour to maximum 2 hours), each surface is transferred into a separate recipient containing recovery liquid and the number of colony-forming units remaining on the reference and test surface are determined by performing serial decimal dilutions and plate culture. The average of the counts is calculated for each type of surface and contact time. The log reduction for each test microorganism is calculated comparing the log of the mean counts recovered from the reference surface and test surface after the selected contact time. The test surface show bactericidal activity when the reduction of minimum 2 log or more is demonstrated.

The test surface shall have flat surfaces and measure between 12 mm and 25 ± 2 mm on the sides or in diameter. The test must be performed with a minimum of 3 replicates per test time (zero time and requested contact time) and 2 for the validation test (8 test parts in total) per test microorganism. That is, a total of 32 pieces for the test with all microorganisms. However, it must be sent at least double that number, in case any result needs to be confirmed or verified; that is, 64 test parts.

All the test surfaces shall be at least rinsed with sterile distilled water before performing the tests. If the samples are not sterile, it is recommended to perform disinfection or sterilization according to the nature of the surface.