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ASTM E2149

Dynamic Shake Flask Test

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

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.

Test Process of ASTM E2149

ASTM E2149 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.

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.

FAQs

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.

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.

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.

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.

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.

The acceptance criteria vary based on the specific test requirements and regulatory demands of the sector. Ideally, at least a 1 log reduction compared to the control sample should be obtained. Higher log reduction signifies higher antimicrobial effectiveness.

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.

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.

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.

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.

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.

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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