ASTM E3160–18. Standard Test Method for Quantitative Evaluation of the Antibacterial Properties of Porous Antibacterial Treated Articles.
Test accredited by ENAC (National Accreditation Entity).
This test method allows evaluating the bactericidal or bacteriostatic properties of porous materials, such as textiles or paper, treated with a biocidal agent. Porous materials, such as textiles, are often treated with antimicrobial agents to reduce the growth of microorganisms during their use, storage, storage prior to washing, or others. In addition, antimicrobial agents can be used in porous materials to reduce or control general microbial growth that can affect the odor, visual, chemical or physical integrity of the material. This procedure can be used to measure both quantitative antibacterial activity and bacteriostatic activity.
To evaluate the properties of the incorporated antimicrobial, samples or pieces of 0.40 g ± 0.05 g of the porous material are used, which are inoculated with a defined suspension of Escherichia coli and incubated for 24 hours. Six pieces of the material treated with the antimicrobial agent, 3 pieces of a material of identical composition without treatment and 2 pieces of a material that promotes bacterial growth should be used as control for validation of the test. From these samples, 3 pieces of the treated material and one of the validation control of the test are used to measure the viable bacteria recovered from the pieces immediately after the inoculation. The rest of the pieces are analyzed to quantify the viable bacteria recovered after 24 hours of inoculation.
Ideally, to measure the bactericidal or bacteriostatic activity, the values of the treated and untreated samples should be compared after incubation. The results of the test are reported as the percent reduction or/and the logarithmic reduction between treated and untreated pieces. However, if pieces of the untreated material of identical composition to the treated porous material are not available, the biocidal activity of the antimicrobial can be calculated by comparing the recovery of viable bacteria from the treated samples immediately after inoculation and after the incubation period. In this case, the results of the test are reported as the percent reduction or/and the logarithmic reduction between the pieces treated immediately after the inoculation and after the incubation period.