ISO 20743:2021

Antibacterial Textile testing 

ISO 20743 is a standardised test method for determining the antibacterial activity of all antibacterial textile products including nonwovens. These textile products may include cloth, wadding, thread, clothing, bedclothes and home furnishings. It is a quantitative method that tests for both bacteriostatic (growth-inhibiting) and bactericidal (bacteria-killing) properties on an antimicrobial fabric.

The ISO 20743:2021 procedure & Assessment

BioLabTests offers the absorption inoculation method using the bacterial species Staphylococcus aureus and Escherichia coli. The method involves growing the bacteria in a liquid culture medium and then suspending them in nutrient broth that affords bacteria the potential to grow during testing.

Controls are always used to validate growth results of test bacteria and validate the test. Test specimens are aseptically inoculated with the bacterial suspensions in triplicate (3 control specimens and 3 testing fabric specimens), ensuring that the inoculum is directly pipetted onto the fabrics and not touching the surface or the cap of the vials.

Things to note 

Methods of testing

There are 3 inoculation methods in ISO 20743 for the determination of antibacterial activity:

ABSORPTION METHOD

An evaluation method in which the test bacterial suspension is inoculated directly onto specimens.

TRANSFER METHOD

An evaluation method in which the test bacteria are placed on an agar plate and transferred onto specimens and incubated for 18-24 hours in humid conditions.

PRINTING METHOD

An evaluation method in which test bacteria are placed on a filter and printed onto specimens and incubated in humid conditions for 1-4 hours.

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ASTM E2149-13A

ASTM E2149-13A

  • Determining the antimicrobial efficacy of antimicrobial agents under dynamic contact conditions

  • Recommended for testing materials such as fabric, paper, powder and granular material

  • Evaluates the activity of an antimicrobial additive within non-leaching materials

ASTM G21-15

ASTM G21-15

  • Determining the effect of fungi on the properties of synthetic polymeric materials in the form of moulded and fabricated articles, tubes, rods, sheets, and film materials

  • Aspergillus brasiliensis is used as the predominant microbe in testing but it is possible to modify the method to suit a client’s specific needs