Antimicrobial activity assessment of textiles: standard methods comparison

Antimicrobial fabrics are increasingly important in a great variety of applications and thus several standard methods to evaluate their efficiency have been developed. However, there is no consensus on the most adequate method to be used. Therefore, aim of this work was to compare the practical applicability of the best known standards: AATCC 147, ISO 20645: 2004, AATCC: 100 and JIS L 1902. Four samples, with different amounts of antimicrobial agents, were used. It was tested 3 qualitative methods (AATCC 147, ISO 20645 and JIS L 1902-Halo method) and 2 quantitative (AATCC 100 and JIS L 1902-Absorption method). For each method, both Gram-positive (Staphylococcus aureus) and Gram-negative (Klebsiella pneumoniae) bacteria were used. Textiles samples assayed did not present diffusible activity, thus only the qualitative results from the AATCC 147 and the Halo method could be analyzed and no differences were observed between them. Therefore, the AATCC 147 or the JIS L 1902-Halo method can be used for a simple and expedite screening of a large amount of samples with or without diffusible antimicrobial activity. In contrast, the ISO 20645 can only be used when diffusible antimicrobial agents are present. Concerning the two quantitative methods, the results showed that the JIS L 1902 method is more sensitive to the amount of antimicrobial agent than the AATCC 100 test. An additional assay also showed that the JIS L 1902 is sensitive enough to distinguish serial dilutions of the antimicrobial agent.