Antimicrobial methods: AATCC

To determine whether the inherent silver and silver coated thread samples would show antimicrobial activity when subjected to soaking wet conditions, the dynamic shake method, ASTM E2149, was performed. The log reduction results after 1 hour and 24 hours incubation at 37 "C (Table 3) show that under soaking wet conditions the inherent silver and silver coated thread samples do exhibit a reduction in bacterial growth. The untreated control samples show an increase in bacterial growth. From these results it would appear the antibacterial activity of inherent silver and silver coated thread samples require soaking wet conditions to exhibit dieir antibacterial properties. As with the AATCC 100 method, the carbonised bamboo sample showed no antimicrobial activity. 

Knitted fabrics used for medical applications - such as in wound dressings - require a zone of inhibition. These may be studied using the AATCC 147 Parallel Streak Standard Method this is an appropriate semi quantitative method for evaluating the antibacterial activity of diffusible antimicrobial agents on treated fabrics. A test result for a fabric treated with the silver salt suspension and a control fabric is presented in Rg. 5.5, where the tested bacteria was Staphylococcus aureus. 

There are a number of test methods that can be used to determine antimicrobial efficacy as well as biocompatibility of treated articles. Standards setting organizations such as the American Society for Testing and Materials (ASTM) and American Association of Textile Chemist and Colorist (AATCC) provide standard test methods that can be used to show antimicrobial efficacy of treated articles. There are also other efficacy test methods that fall outside the purview of these two organizations that are very effective. The ISO Technical Committee 194 has developed the ISO 10993 biocompatibility series which address the biological evaluation of medical devices including standards for those treated with antimicrobials. 

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