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ISO 20645

Determination of Antibacterial Activity of Textile Fabrics

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ISO 20645 : 2004 – Textile Fabrics – Determination of Antibacterial Activity – Agar Diffusion Plate Test

ISO 20645 test is used to determine the antibacterial activity of diffusible antimicrobial agents on textile materials. This standard outlines a method to evaluate if antibacterial agents applied on woven, knitted and other flat textiles are effective in inhibiting or reducing the growth of bacteria.

The scope of textile products that can be tested with ISO 20645 guideline include hygienic finishes of hydrophilic, air-permeable materials or antibacterial agents incorporated in the fibre.

ISO 20645 Test Method

  • Sample fabric materials are placed on two-layer agar plates. The lower layer only consists of agar medium and the upper layer is inoculated with test bacteria. The textiles are tested on both sides.
  • At the end of the incubation period, petri plates are examined for antimicrobial activity.
  • The antibacterial activity is determined by examining bacterial growth around the contact zone between agar and sample fabric and measuring the zone of inhibition.

Importance of ISO 20645 Test

  • Antimicrobial fabrics are designed to prevent or reduce the accumulation of harmful microbes on fabric surfaces while minimizing the risk of infection transmission. Such fabrics are commonly used in various applications, including healthcare settings, sportswear, and everyday apparel, where cleanliness and protection against microorganisms are essential.
  • International Organization for Standardization (ISO) has developed various standards for antimicrobial textiles to ensure product efficacy before practical use. ISO 20645 is one of widely accepted standards that outlines the testing methodologies and performance criteria to determine the antimicrobial efficacy of the textiles having diffusible activity.

At MIS, we offer ISO 20645 testing services that are perfectly curated to help clients to assess antibacterial performance of their textiles materials. Additionally, our antimicrobial textile portfolio also comprises protocols like ISO 20743 and AATCC 100.

Our aim is to provide hustle free solutions for all our client needs. In this regards, MIS has a team of experts to design and maintain SOPs for conducting routine antimicrobial analysis in our labs. We generate scientific reports with precision and accuracy.

To request a quote for ISO 20645 testing or want to know more about our microbiology testing services, contact our microbiology experts today.


ISO 20645 is a standardized method to evaluate antibacterial activity of textile materials with diffusible activity. The results of the ISO 20645 test provide an assessment of the antimicrobial performance of textiles by examining the zone of inhibition around sample material.

ISO 20645 test is applicable to hygienic finishes applied to hydrophilic, air-permeable materials and other antibacterial textile products.

ISO 20645 test takes 3-4 weeks to complete.

At Microbe Investigations, we test for ISO 20645 using the following microbial strains: Staphylococcus aureus (ATCC 6538 or NCCB 46064), Escherichia coli (ATCC 11229 or NCCB 1500), and Klebsiella pneumoniae (ATCC 4352 or NCCB 89160).

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