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AATCC 147 Antibacterial Activity Assessment of Textiles (Parallel Streak Method)
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Summary
AATCC 147 or Parallel Streak Method is a qualitative test that evaluates the antibacterial activity of treated textiles by observing zones of inhibition against specific bacteria on agar plates. It is a quick and cost-effective test method for manufacturers, to validate antibacterial claims, substantiate product development, and produce data for regulatory use.
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Quick understanding of the test
AATCC 147 - Antibacterial Activity Assessment of Textile Materials Using the Parallel Streak Method
- Staphylococcus aureus ( ATCC 6538P)
- Klebsiella pneumoniae (ATCC 4352)
- Nutrient agar plate is inoculated with a bacterial strain.
- The treated textile sample is placed on the inoculated agar.
- Plate is incubated at a specified temperature for a defined period.
- The bacterial growth around the fabric sample is examined.
- The size of the clear zone of inhibition is measured to determine antibacterial activity.
- Helps with the rapid assessment of the antimicrobial activity of textile materials.
- Assists manufacturers in meeting regulatory and quality standards.
Turnaround Time
Passing criteria
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What is AATCC 147 Testing?
AATCC 147 is a standard test method that is also known as the Parallel Streak Method. It provides a relatively rapid and simple qualitative method for measuring the antibacterial activity of diffusible antimicrobial agents on treated textile materials. However, it is important to note that the method is not applicable to materials that are likely to encapsulate and suppress the diffusion of antibacterial agents or contain substances that neutralize the antibacterial activity.
Scope of AATCC 147 Standard
The test method is applicable to all textile products regardless of the type of antibacterial agents. It includes –
- Clothes
- Waddings
- Threads
- Bedclothes
- Home furnishings
- Other porous materials
Test Organisms Used in AATCC 147
Mandatory strains:
Staphylococcus aureus (ATCC 6538P)
Klebsiella pneumoniae (ATCC 4352)
Additional Strains:
Escherichia coli(ATCC 8739)
Pseudomonas aeruginosa (ATCC 15442)
Enterococcus hirae (ATCC 10541)
MRSA (ATCC 33591)
Salmonella enterica (ATCC 10708)
Candida albicans (MTCC 3017)
Other strains can be added according to requirement.
Test Sample
Test samples (non-sterile) are cut into rectangular pieces of dimensions 25 x 50 mm.
AATCC 147 Test procedure
Preparation of nutrient agar plates and inoculation
- Molten nutrient agar medium is poured into Petri dishes and allowed to solidify.
Placement of textile Specimen
- Five parallel streaks of bacterial suspension are made across the agar surface using a sterile inoculation loop.
- The treated test specimen (25 x 50 mm) is placed transversely across the streaks, making sure of a proper contact with the agar surface. The same procedure is done for control (Untreated) sample.
Incubation conditions
- The inoculated plates are incubated with the test specimens at 37 ยฑ 2ยฐC for 18-24 hours.
Zone of inhibition measurement
- Post incubation, petri dishes are observed for interrupted bacterial growth in the streaks and zone of inhibition that occurs due to the presence of the antibacterial agents.
How are results evaluated?
In AATCC 147, evaluation of results is done by visually observing growth of bacterial patterns on agar after incubation, analysing the presence or absence of inhibition around the specimen.
Post Incubation, a clear area of interrupted growth beneath and beyond edges of the test material indicates antibacterial activity of the specimen.
Regulatory & Market Relevance of AATCC 147
AATCC 147 plays a crucial role in evaluating antibacterial activity in textiles, specifically during early-stage product development. However, it is a qualitative test and does not provide a quantitative value. AATCC 147 testing supports technical documentation, R&D validation, and comparative performance studies.For regulatory approval according to frameworks like the Biocidal Products Regulation or by the Environmental Protection Agency, quantitative data is usually required.
Why textiles fail AATCC 147 ?
Textiles often fail AATCC 147 as the antimicrobial chemistry is non-diffusible, preventing the formation of a visible inhibition zone despite potential contact activity. Other common reasons can be low active concentration, poor fixation to fibers, encapsulation or binders that limit diffusion, and chemical deactivation of the antimicrobial agent during processing or testing.
When should you choose AATCC 147?
AATCC 147 is applied when a product is treated with diffusible antibacterial agents and needs rapid, qualitative screening during early-stage product development. It is specifically useful when visible zone-of-inhibition data is required and for comparing treated against untreated fabrics before proceeding to quantitative efficacy testing.
Strengths of AATCC 147 Test Method
The AATCC standards for textile testing method have certain strengths that make it a preferred choice to assess antibacterial activity in textiles:
- Simplicity: The test is simple to perform and provides a quick and efficient method to assess textile samples.
- Cost-effective: This test is relatively cost-effective as it needs minimal media requirements and no involvement of sophisticated instruments.
- Clear results: The zone of inhibition gives a clear visual representation of the antimicrobial effectiveness. This helps interpret the results in a simpler manner.
Limitations of AATCC 147 Test Method
This method is not suitable to materials that encapsulate and interrupt the diffusion of the antibacterial agent or if they contain components that can potentially neutralize its antimicrobial effects.
AATCC 147 vs Other Standards
Category | AATCC 147 | ISO 20645 | AATCC 100 |
Purpose | To qualitatively evaluate antibacterial activity of treated textiles by observing zones of inhibition. | To qualitatively assess antibacterial activity of textiles by measuring zone of inhibition. | To quantitatively evaluate the antibacterial efficacy of treated textiles by measuring the reduction of viable bacteria. |
Method Principle | Parallel streak method | Agar diffusion plate method | Shake flask / direct inoculation method |
Test Type | Bacteriostatic | Bacteriostatic | Bactericidal |
Mandatory test organisms | Staphylococcus aureus ( ATCC 6538P) and Klebsiella pneumoniae (ATCC 4352). | Staphylococcus aureus(ATCC 6538 or NCCB 46064), Escherichia coli (ATCC 4352 or 89160) or Klebsiella pneumoniae (ATCC 11229 or NCCB 1500) | Staphylococcus aureus (ATCC 6538P), Klebsiella pneumoniae (ATCC 4352) |
Applicability | Mainly applicable in the US, early-stage testing of textiles | International standard, recognized for global compliance | Mainly applicable for the US, widely used for product claim substantiation |
Scope of products | Diffusible antimicrobials on treated hydrophilic textile surfaces | Hydrophilic textile and miscellaneous goods | Hydrophilic textile and other porous textile materials |
Passing criteria | Presence of zone of inhibition around the specimen | Presence and/or size of zone of inhibition and/or absence of growth under the specimen | % reduction of bacteria compared to control |
Why choose our Lab for AATCC 147 testing
At Microbe Investigations Switzerland, we provide AATCC 147 testing to accurately determine the antimicrobial activity of your textile products. Our specialized testing ensures that your textiles meet the highest standards for antimicrobial efficacy, safeguarding consumer health and product quality. We offer both qualitative (AATCC-147) and quantitative methods (AATCC 100, JIS L 1902, ISO 20473) for antibacterial testing of textiles.
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Frequently Asked Questions
DR. Martinoz Scholtz
AATCC 147 is a qualitative agar diffusion test where treated textile samples are placed across bacterial streaks on agar to visually assess inhibition of bacterial growth.
The clear area (no bacterial growth) around the textile sample is measured to determine the zone of inhibition which indicates the antibacterial efficacy of the fabric.
AATCC 147 evaluates antibacterial activity based on the zone of inhibition while AATCC 100 is a quantitative test that measures the percentage reduction in bacteria over time.
No, AATCC 147 is a qualitative screen for antibacterial activity. It does not provide precise numeric reduction counts
Standard organisms are Staphylococcus aureus ( ATCC 6538P) and Klebsiella pneumoniae (ATCC 4352), other strains may be used based on requirement
This test typically takes 3-4 weeks.
Nutrient agar is mostly used as it supports the growth of a wide range of bacteria. However, specific types of agar can be used depending on the bacterial strain being tested.
Changes in temperature and incubation time can affect the growth rate of the bacteria and the performance of the antimicrobial agents thus providing inaccurate results.
No, this test is specifically designed for textile materials.
This test provides a standard method to demonstrate the presence and effectiveness of antibacterial agents in textiles thus supporting product development and quality assurance.
Yes the standard can be used to test silver-based antibacterial-treated fabrics.
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