Antimicrobial agents
Standard / Test method
DIN EN ISO 20645
Assessment of antibacterial activity in treated textiles and other suitable samples using agar diffusion testing based on DIN EN ISO 20645.
Overview
DIN EN ISO 20645 specifies an agar diffusion method for assessing antibacterial treatments on textile fabrics.
The method is often called an inhibition-zone test and can support screening of antibacterial properties.
The standard evaluates bacterial growth beneath the textile specimen and any inhibition zone surrounding it. Such zones form when antibacterial substances diffuse into the agar.
For antimicrobial agents, formulations or other materials, suitability and necessary adaptations are assessed for each project. Test conditions such as sample type, specimen dimensions, incubation time and test bacteria can be agreed according to the testing objective.
Typical applications
Antibacterial agent screening
Screening of antibacterial agents using a suitable, project-specific agar diffusion test.
Material assessment
Assessment of antibacterial properties of treated textiles and other suitable materials.
Product development
Assessment of new formulations and antimicrobial treatments using adapted test designs.
Frequently asked questions
What is an inhibition-zone test?
An inhibition-zone test assesses whether antibacterial substances diffuse from a sample into the agar and inhibit bacterial growth.
What does the size of an inhibition zone indicate?
The size of an inhibition zone is influenced by both antibacterial activity and the ability of a substance to diffuse through the agar. A larger inhibition zone therefore does not automatically indicate greater efficacy. DIN EN ISO 20645 also evaluates bacterial growth beneath the textile specimen.
Which products is DIN EN ISO 20645 suitable for?
The standard applies primarily to textile fabrics with antibacterial treatments. Other materials can be tested with suitable adaptations. For antimicrobial agents or formulations, suitability and test design must be assessed for each project.
What is the difference between DIN EN ISO 20645 and MIC testing?
DIN EN ISO 20645 qualitatively assesses bacterial growth beneath the specimen and any inhibition zone in the agar. MIC testing based on DIN 58940-8 determines the lowest concentration of an antimicrobial agent that prevents visible growth.