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.
- 3 wash solutions:
- 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.
- 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.