ASTM E2149: 2020

Standard Test Method for Determining the Antimicrobial Activity of Immobilized Antimicrobial Agents Under Dynamic Contact Conditions

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Quick understanding of the test

ASTM E2149: 2020 - Standard Test Method for Determining the Antimicrobial Activity of Immobilized Antimicrobial Agents Under Dynamic Contact Conditions

ASTM E2149 evaluates the antibacterial activity of non-leaching antimicrobial agents on treated materials under dynamic conditions.
Applicable to a wide range of products, including fabric, paper, powder, and more.
  • Treated and untreated samples are placed in different flasks and inoculated with bacterial suspension. 
  • The flasks are shaken to ensure good contact between bacteria and fabric samples. 
  • Microbial concentrations in the flasks containing treated and untreated specimens are measured at specified time intervals to evaluate antimicrobial activity. 

Turnaround Time

It typically takes 3-4 days
The result is evaluated by comparing the bacterial count in the treated sample to the untreated control sample after incubation.

Passing criteria

A product must achieve atleast 1 log reduction in bacterial count compared to the untreated control.

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Abstract

The ASTM E2149 standard is a test method for determining the efficacy of antimicrobial agents mounted on a surface under dynamic contact conditions. This quantitative test assesses the performance of non-leaching antimicrobial agents on microbial samples under dynamic conditions. Often referred to as the dynamic shake flask test, it ensures adequate contact between bacteria and a treated sample by shaking the sample in a bacterial suspension for nearly one hour. This test is crucial for evaluating material performance against microbial attack in various fields.

Products tested

The ASTM E2149 test is versatile and can be applied to a wide range of products including

  • Fabric
  • Paper
  • Powder
  • Granular materials
  • Other solids

These products are characterized by irregular shapes or hydrophobic surfaces that render the use of conventional testing techniques impractical. 

Preparations for the test

Preparing the bacterial inoculum

Ideally, the test requires bacterial inoculum from a culture that is usually 18 hours old and is in a logarithmic phase of growth. The starter culture is made by diluting the logarithmic phase culture with a sterile buffer solution to the desirable concentrations. To ensure that the inoculum is accurate and precise, dilution and standardization must be done carefully.

Preparing the test specimen

Every treated and untreated specimen should weigh between 0. 5 g and 2 g.

Commonly used organisms

The organisms used for the test are Staphylococcus aureus (ATCC 6538P), Klebsiella pneumoniae (ATCC 4352), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 15442), Enterococcus hirae (ATCC 10541), MRSA (ATCC 33591), Salmonella enterica (ATCC 10708), Candida albicans (MTCC 3017). 

Test procedure

Preparing the specimens

Both antimicrobial-treated and untreated specimens of each testing material are prepared. These specimens are placed separately in 250 mL screw-cap Erlenmeyer flasks.

Adding bacterial suspension

The suspension with a known amount of bacteria is added to each flask containing the test specimen. This ensures contact between the bacteria and the treated and untreated materials.

Dynamic shaking

The flasks are shaken using a wrist action shaker to ensure good contact between the bacteria and the treated substrate.

Determining microbial concentration

Microbial concentrations in the flasks containing treated and untreated specimens are determined at specific time intervals, such as 0, 1, or 24 hours. This step assesses the antimicrobial activity over time.

Benefits

Accurate measurement of antimicrobial activity

This test provides an accurate measure of the antimicrobial efficacy of an immobilized agent, making it crucial for industries relying on prolonged antimicrobial activity.

Versatility

This standard can test products with different shapes and hydrophobic properties, making it valuable for many industries.

Realistic simulation of use conditions

The dynamic nature of the test closely mimics actual usage conditions, offering a realistic evaluation of antimicrobial activity.

Regulatory acceptance

This test is accepted by many regulatory bodies and industry standards, facilitating product approval and market entry.

Applications

Healthcare

This test is essential in the medical field to ensure pathogen-free surfaces, devices, and materials. It confirms the antimicrobial properties of medical textiles, wound dressings, and implantation devices.

Consumer products

The antimicrobial efficacy of consumer products such as kitchen tools, cutting boards, and clothing can be leveraged to increase sales. This test provides manufacturers with a reliable method to support their claims of antimicrobial features.

Industrial and environmental applications

The method applies to assessing the efficacy of antimicrobial coatings in HVAC, water filtration units, and other industrial applications where microbial contamination may be a problem.

Conclusion

At Microbe Investigations Switzerland, we specialize in conducting ASTM E2149 tests to determine the antimicrobial activity of immobilized agents under dynamic contact conditions. Our expert team uses advanced methodologies to deliver precise and reliable results ensuring your products meet the highest standards for antimicrobial efficacy. Trust MIS to provide comprehensive testing solutions that support your product development and regulatory compliance.

You can connect with our experts to discuss your requirements for the test today. We will be happy to assist you.

Frequently Asked Questions

DR. Martinoz Scholtz

MIS Labs
1. What is the ASTM E2149 test?

ASTM E2149 is a sensitive test used for determining the antimicrobial activity of immobilized antimicrobial agents under dynamic contact conditions. It measures the antimicrobial activity of non-leaching, irregularly shaped, or hydrophobic surfaces.

2. What Products Can Be Tested Using the ASTM E2149 Test?

The test is applicable to measuring the antimicrobial activity of non-leaching (immobilized and not water-soluble), irregularly shaped, or hydrophobic surfaces. Products tested include fabric, paper, powder, granular material, and other solids.

3. What is the Turnaround Time for the ASTM E2149 Test?

The test takes 3 to 4 days to complete.

4. What Types of Microorganisms Are Used in ASTM E2149 Testing?

The microorganisms typically include common bacteria such as Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative). Other microorganisms like Pseudomonas aeruginosa, Klebsiella pneumoniae, and fungi like Candida albicans may also be used depending on the specific requirements of the test.

5. What is the shake flask method?

The shake flask method is used in a laboratory to assess the antibacterial efficacy of treated materials. In this method, treated samples are cultured in a nutrient broth containing a particular microorganism. The flask is agitated to facilitate better distribution and contact of the microorganisms with the treated material. After the incubation period, the decrease in microbial count is measured to determine the antimicrobial effectiveness.

6. Which Products Typically Require ASTM E2149 Testing?

Commodities often tested include textiles, plastics, coatings, polymers, and other substances containing antimicrobial agents. These products are especially employed in healthcare, consumer goods, food packaging, and other areas where there is a necessity to prevent microorganism growth.

7. How Can I Prepare My Product Samples for ASTM E2149 Testing?

Before conducting the test, ensure that the product samples are cut to appropriate sizes according to the protocol. The samples should be in a germ-free state and handled aseptically to reduce interference by unwanted organisms. Follow the specific sample preparation procedures given by the testing laboratory.

8. How Does ASTM E2149 Specifically Assess the Antimicrobial Properties of Textiles?

This test determines the ability of coated or treated textile samples to control microbial growth. It involves exposing the tested material to a microbial growth medium containing viable microbial cells. Each sample-containing flask is shaken to facilitate contact between microorganisms and the treated textile. Subsequently, microbial count is determined, followed by the evaluation of microbial reduction to assess the antimicrobial effectiveness of the textile.

9. Can ASTM E2149 Testing Help in Extending the Shelf Life of Antimicrobial Products?

Yes, this test can help in extending the shelf life of antimicrobial products by providing information on how effective antimicrobial treatments are over a certain period. Manufacturers can justify claims about the longevity and durability of their products’ antimicrobial properties by demonstrating sustained antimicrobial activity.

10. How Does This Test Differ for Various Materials Like Plastics and Textiles?

While the general principle of the test is similar across materials, certain parameters such as sample preparation, handling, and exposure conditions may vary depending on the material type. For instance, textiles may need different sample sizes and agitation speeds compared to plastics. 

11. Are there any industry-specific requirements that make this test essential?

Yes, some specific industries like healthcare, food packaging, and consumer products may require this test by regulations or customer requirements. These requirements ensure that antimicrobial treatments are effective in reducing microbial contamination to safe levels for product consumption.

12. How does ASTM E2149 testing ensure compliance with international antimicrobial standards?

This testing helps maintain compliance with international antimicrobial standards by providing a method to test antimicrobial performance. The data generated can be used as evidence of antimicrobial efficacy necessary for claims and compliance with these standards.

13. What are the potential limitations of ASTM E2149 testing for my product?

Potential limitations include the focus on laboratory conditions that cannot completely simulate real-use conditions. Factors such as degradation, climatic conditions, and complex microbial communities present in the real world are not accounted for in this test. Additionally, the test primarily assesses bacterial reduction and may not appropriately gauge antifungal or antiviral properties.

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