ASTM E2406: Evaluation of Laundry Sanitizers and Disinfectants for Use in High-Efficiency Washing Operations

Link: https://www.astm.org/Standards/E2406.htm

Purpose and Goals

  • Evaluate and compare the antimicrobial efficacies of laundry sanitizers against a variety of microbes in laboratory-controlled testing. 
  • High-efficiency automatic laundry operations typically use very low water volumes and thus present a worst-case scenario challenge for laundry sanitizers. 

Materials and Methods

  • This testing will be a modification of ASTM International’s Standard Test Method E2406 – Evaluation of Laundry Sanitizers and Disinfectants for Use in High-Efficiency Washing Operations.
    • Note: An alternative method for a similar evaluation in a common top-loading style washing machine is ASTM E2274 (link: https://www.astm.org/Standards/E2274.htm)
  • Test fabric swatch carriers will be inoculated with a liquid microbial suspension, dried, and then placed into a pre-formed spindle of sterile ballast fabric (to simulate worst-case scenario exposure to the laundry sanitizer). Carriers will be “washed” with the test solution of water and laundry sanitizer/disinfectant inside separate wide-mouth bottles on an agitator for the specified exposure time. After washing, the carriers and wash solutions will each be neutralized and the microbes cultured in growth media. 
    • For laundry disinfectants: Cultures will be plated to provide qualitative growth (+) or no growth (-) results for each carrier or wash solution tested.
    • For laundry sanitizers: Cultures will be dilution-plated to provide quantifiable viable microbial burden data for each carrier or wash solution tested. 
  • This testing will include 5% organic soil (serum) in the inoculum solution. 
  • Each test will include one microbial strain:
    • Methicillin-resistant ​Staphylococcus aureus​ ATCC 33592 (MRSA) bacteria
    • Staphylococcus aureus​ ATCC 6538 (MSSA) bacteria
    • Carbapenem-resistant Klebsiella pneumoniae ATCC 4352 or BAA-1705 (KPC) bacteria
    • Pseudomonas aeruginosa ATCC 9027 or 15442 bacteria
    • Clostridioides difficile ATCC BAA-1870 or 43598 (formerly known as Clostridium difficile) bacterial spores
  • Each test will include 27 total data-points:
    • 3 wash solutions: 
      • water only (as a negative control)
      • bleach water (as a positive control), per CDC guidelines
      • HOCl water (concentration TBD)
    • 3 bottles of each wash solution.
    • 3 replicate fabric swatch carriers in each bottle. 
  • Per CDC guidelines for infection control of laundry in healthcare environments, the water temperature used will be 160°F, and the wash time will be 25 minutes. 
  • Note: Optional GLP services are available for an additional 25% fee.

Data Analysis

  • For Sanitizers only: Data will be calculated to determine the quantifiable bacterial burden in colony-forming units per carrier or mL (CFU/carrier or CFU/mL) remaining in each test component.
  • For Disinfectants and Sanitizers: Data will be analyzed to determine the consistency between replicate discs.
  • For Sanitizers only: Data will be analyzed to compare the efficacies of each testing condition to determine the percent reductions and log reductions of microbial burdens compared to controls. 

Typical Turn Around Time

  • Bacterial/fungal (per strain): 2-4 weeks following receipt of the test materials, depending on the wash intervals requested.