SMTL are able to test the antimicrobial activity of a range of different materials using national and international standards. Products which have been examined include Medical Devices such as dressings, bandages and urology products, Textiles and Plastics. Whilst these standards recommend using particular test conditions, alternatives may be used at the request of the client or by recommendation from SMTL.

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Several methods are available depending upon whether the antimicrobial agent is immobilised or able to leach from the product.

Antimicrobial Dressings:

SMTL offer a range of  antimicrobial tests for wound dressings, especially for silver-containing dressings. Some of that work has been published (see below and www.medidex.com/research.html).  SMTL staff are also involved in developing the new European standard for the antimicrobial testing of wound dressings.

ASTM E2149:

Standard Test Method for determining the antimicrobial activity of immobilised antimicrobial agents under dynamic contact conditions.

ASTM E2149 is a quantitative test method which is used to measure the antimicrobial activity of materials (for example textiles and hard surfaces) treated with non-leaching (non-water soluble) antimicrobial agents. The ASTM E2149 test, known as the shake flask method, allows the testing of products of different shapes and sizes. Standard conditions specify a contact time period of 1 hour using Escherichia coli.

BS EN ISO 20743:

Textiles, Determination of antibacterial activity of antibacterial finished products (equivalent to JIS L 1902).

BS EN ISO 20743 specifies quantitative methods to determine the efficacy of antimicrobial treatments on textiles. The standard gives the choice of three different methods. The client can select the most suitable method depending upon the nature and intended application of the product. Standard conditions specify a contact time period of 24 hours using Staphylococcus aureus and Klebsiella pneumoniae in triplicate.

AATCC Test Method 100:

Antibacterial Finishes on Textile Materials.

AATCC Test Method 100 is a quantitative test method for evaluating the activity of samples treated with leaching antimicrobials. Standard conditions specify a contact time period of 24 hours using Staphylococcus aureus and Klebsiella pneumoniae.

BS EN IS0 20645:

Textile fabrics. Determination of antibacterial activity. Agar diffusion plate test.

BS EN ISO 20645 is essentially a qualitative test method for determining the effect of antibacterial treatments applied to woven, knitted and other flat textiles, although semi-quantitative information can be obtained when comparing different concentrations of the same product. A minimum diffusion of the antibacterial treatment into the test agar is necessary with the procedure. The method is not suitable for testing materials treated with antimicrobials that react with the agar. Satndard conditions specify a contact time period of 18-24 hours using Staphylococcus aureus and either Escherichia coli or Klebsiella pneumoniae. Tests on four specimens are necessary and shall be carried out on both sides of the specimens.

AATCC Test Method 147

Antibacterial Activity Assessment of Textile Materials: Parallel Streak Method.

The parallel streak method is a qualitative method to detect the antibacterial activity of diffusible antimicrobial agents on textile materials. The standard organisms are Staphylococcus aureus and Klebsiella pneumoniae. This method is particularly useful for thin woven materials.


For products where standard methods may not be appropriate or cannot be used, SMTL have developed bespoke test methods.

If you have a product you wish to have tested for antimicrobial activity, please contact:- biological@smtl.co.uk

References

  • Thomas S, McCubbin P. J Wound Care. 2003 Mar;12(3):101-7. A comparison of the antimicrobial effects of four silver-containing dressings on three organisms.
  • Thomas S, McCubbin P. An in vitro analysis of the antimicrobial properties of 10 silver-containing dressings. J Wound Care. 2003 Sep;12(8):305-8.

  • Thomas S, McCubbin P. Silver dressings: the debate continues. J Wound Care. 2003 Nov;12(10):420; discussion 420

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