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PAS 2424: 2015 – Quantitative Surface Test for Antimicrobial Efficacy of Disinfectants (Bactericidal and/or Yeasticidal) on Hard Non-porous Surfaces
PAS 2424: 2015 quantitatively tests the residual antimicrobial activity of disinfectants on hard, non-porous surfaces. This test standard is essential for products claiming residual activity, particularly those that are used in critical sectors such as food processing, healthcare, and institutional settings. It establishes the effectiveness of a disinfectant against a range of bacteria and yeasts.
The test also simulates conditions of practical use including surface abrasion and contamination in order to ensure that a disinfectant is effective even after wear and tear over time. Products undergoing this test can therefore prove their product claims regarding long-term efficacy against antimicrobial action, making it an essential requirement for testing disinfectants designed for high-risk areas.
PAS 2424 test standard
PAS 2424 has been formulated to work in combination with EN 13697. While PAS 2424 is used to assess the residual antimicrobial activity of products, the EN 13697 tests the initial antimicrobial activity of disinfectants. Meeting the requirements defined in PAS 2424 can ensure that a product performs well under specific abrasion cycles and exposure to microorganisms, ensuring its claims for extended protection against microorganisms. This test method is particularly effective in demonstrating the reduction in microbial contamination even after exposure for 24 hours under challenging conditions.
Importance of PAS 2424 test
The PAS test validates the long-term effectiveness of disinfectants, especially those that are claimed to have a 24-hour residual activity. The reliance of the healthcare, food processing, and public facilities industries on residual antimicrobial activity for the prevention of contamination and infection increases the significance of this test method in verifying these claims and allows manufacturers to ensure their products meet the required industry safety and efficacy criteria.
PAS 2424 test conditions
The test for PAS is carried out under standardized conditions in order to obtain reproducible and reliable results. It generally comprises:
- Temperature: Carried out at 20°C.
- Interfering substance: To closely mimic clinical conditions, an interfering agent like 3.0 g/L bovine albumin is used.
- Contact time: Bacteria are exposed to the disinfectant for a contact time of 5 minutes, while yeasts have a contact time of 15 minutes. (The contact time can be modified depending on the manufacturer’s instructions.)
- Abrasive cycles: Abrasion cycles are used to replicate wear and re-contamination of the test surface.
PAS 2424 test requirements
Test organisms
The products are tested for efficacy against the following strains:
- Pseudomonas aeruginosa (ATCC 15442)
- Staphylococcus aureus (ATCC 6538P)
- Escherichia coli (ATCC 8739)
- Enterococcus hirae (ATCC 10541)
- Candida albicans (MTCC 3017)
- Klebsiella pneumoniae (ATCC 4352)
- MRSA (ATCC 33591)
- Salmonella enterica (ATCC 10708)
Passing criteria
To pass the test, the product must demonstrate at least ≥4 log reduction in the microbial count which is indicative of a 99.99% reduction in viable microbial organisms. Results of the PAS test shall only be considered valid if the product acquired a ≥4 log reduction in compliance with EN 13697 test, carried out under the specified test conditions i.e., specified contact time, temperature, and organic load.
PAS 2424 test methodology
- Preparation of test discs
Steel discs are inoculated with the recommended test microorganisms and allowed to dry.
- Product application
Application of test product: The disinfectant product under test is applied to five of the inoculated discs, additional five other discs are exposed to hard water (control). The application may use the concentrated or diluted form of the test product depending on the product’s intended use.
- Abrasion and re-contamination
The treated and control discs are subjected to three cycles of abrasion after a contact period of 24 hours to simulate the wear and re-contamination events that would occur in the practical conditions.
- Post-contact period and incubation
After 24 hours, all treated discs along with the corresponding control discs, are reinoculated with the test microorganism. An interfering substance like 3.0 g/L of bovine albumin is added to the discs and incubated under controlled conditions at 20°C for the specified contact time.
- Neutralization
After incubation, the discs are transferred to a neutralizing solution, which halts the action of the disinfectant and prevents further microbial activity.
- Bacterial recovery and plate count
The neutralizing solution is analyzed using the plate count method to detect the presence of any surviving microorganisms.
- Calculation of residual efficacy
The residual antimicrobial activity is determined by comparing the difference in microbial reduction between treated discs and control discs.
Compliance and industry standard for PAS 2424 test procedure
The PAS standard aligns with EN 13697, the international European standard for disinfectant efficacy testing. Compliance with this standard ensures that the product meets the international standards for residual antimicrobial activity, thus providing manufacturers with the ability to market their products as effective against a wide range of pathogens.
The products tested under this standard should also comply with the prescribed test conditions of EN 13697 and demonstrate a significant reduction in microbial load to be considered as a valid test.
Strengths of PAS 2424 test standard
- Simulates real-life conditions: The use of abrasion cycles combined with microbial challenges replicate natural usage conditions in the product..
- Extended efficacy: The test confirms the extended antimicrobial efficacy (residual efficacy) of products and can support claims for 24-hour protection.
- Versatile: The standard is applicable to multiple industries from the healthcare and food-processing industry to public space, or institutions.
- Aligns with EN standards: PAS test extends the efficacy requirements set by EN 13697 and adds an additional layer of validation.
Benefits of PAS 2424
- Enhanced product credibility: With products that comply with PAS, manufacturers can make valid claims for extended antimicrobial activity, which is an indispensable requirement for consumer trust.
- Wider market access: Successful products can achieve wider market opportunities as they meet stringent international requirements for hygiene.
- Improved safety: The test ensures that the products used in critical areas such as hospitals or food processing units, provide long-term protection from harmful microorganisms.
Conclusion
PAS 2424 is a standard test to determine the residual efficacy of antimicrobial disinfectants under realistic conditions for long-term efficacy. The test standard ensures products comply with strict criteria for long-term protection and thereby contributes to safeguarding public health and hygiene. Manufacturers can validate their product’s claims scientifically and obtain internationally recognized certifications.
Microbe Investigations is a leading microbiology testing service provider across the globe. Our testing facilities are well equipped with the most advanced testing equipment and highly skilled microbiologists and technical staff. Our antimicrobial testing services include the use of both standardized and customized protocols to suit the customer’s requirements.
We specialize in testing the efficacy of textile finishes, coatings, and disinfectant products, with a focus on quality, quick turnaround, and cost efficiency. Enhance your product’s credibility and compliance with our comprehensive PAS 2424 testing service.
Connect with our experts today to schedule your PAS 2424 testing and ensure your product meets the highest standards of residual antimicrobial efficacy.
FAQs
PAS 2424 test is a quantitative non-porous surface test that evaluates the residual bactericidal and/or yeasticidal activity of chemical disinfectant products.
PAS 2424 test is intended for disinfectant formulations used in homes, schools, hospitals, nursing homes, and industrial areas.
PAS 2424 test takes 3-4 days to complete.
At Microbe Investigations, we understand the need for accuracy and speed. We test for PAS 2424 using the following bacteria: Pseudomonas aeruginosa (ATCC 15442), Escherichia coli (ATCC 8739), Staphylococcus aureus (ATCC 6538P), Enterococcus hirae (ATCC 10541), Klebsiella pneumoniae (ATCC 4352), MRSA (ATCC 33591), Salmonella enterica (ATCC 10708), Candida Albicans (MTCC 3017). Additional strains can be added on request.
PAS tests are conducted at 20°C with 3.0 g/L bovine albumin as an interfering substance. The contact time is 5 minutes for bacteria and 15 minutes for yeast.
PAS test is not mandatory however, it is highly recommended for products claiming long-term residual antimicrobial activity.
Industries that manufacture disinfectant products with residual antimicrobial activity benefit from this certification.
No the PAS test is applicable only to disinfectant products used on hard non-porous surfaces to assess their residual antimicrobial activity.
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