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ASTM E3135 – Determining Antimicrobial Efficacy of Ultraviolet Germicidal Irradiation Against Microorganisms on Carriers with Simulated Soil

Purpose and Goals

  • Evaluate and compare the antimicrobial efficacies of a novel disinfectant product(s) against a variety of microbes on different test conditions in laboratory-controlled testing. 
  • This testing will be performed:
    • by our staff at ResInnova Laboratories, and/or 
    • by the client at an off-site location, with the tested materials then shipped overnight to ResInnova Laboratories for analysis. 

Materials and Methods

  • This testing will be a modification of the International Standard Test Method ASTM E3135.
  • Nonporous surface carriers (1” x 1” polycarbonate slides) will be inoculated with a liquid microbial suspension distributed in ten droplets of 1 µL each over a 22 mm x 22 mm surface area, dried, and then…
Testing by staff at ResInnova Laboratories:Testing by Client at Offsite Location:
Placed at specified test locations for exposure to the disinfection product.Shipped to the client for exposure to the disinfection product. After exposure, the carriers will need to be shipped overnight (shipping to be provided by the client) to ResInnova Laboratories for recovery and analysis.
  • The microbes from each carrier will be recovered into a solution which will be dilution-plated to provide quantifiable viable microbial burden data for each carrier tested. 
  • This testing will include 5% organic soil (fetal bovine serum) in the inoculum suspension. 
  • Each test will include one microbial strain:
    • Staphylococcus aureus​ ATCC 6538 Gram-positive bacteria
    • Klebsiella pneumoniae ATCC 13048 Gram-negative bacteria
    • Escherichia coli ATCC 25922 Gram-negative bacteria
    • Pseudomonas aeruginosa ATCC 15442 Gram-negative bacteria
    • Candida auris ATCC MYA-5001 fungus 
    • Candida albicans ATCC 10231 fungus
    • Bacillus spizizenii ATCC 6633 (formerly B. subtilis) Gram-positive bacterial spores
    • Clostridioides difficile ATCC 43593 (formerly Clostridium difficile) Gram-positive bacterial spores
  • Please note: C. difficile spores are available for offsite testing ONLY to professionals experienced with handling infectious materials. BioSafety Level 2 documentation will be required.
  • Each test will include 30 total carriers:
    • 5 exposed carrier locations: TBD. 
    • 1 exposure time: TBD minutes. 
    • 3 replicate carriers will be tested for each testing condition (sample size n=3).
    • 3 replicate carriers will also be kept unexposed as negative controls. 
  • Optional GLP services are available for an additional fee. (Not available for off-site testing.)
  • Optional dosimeter and/or radiometer data collection/analysis services are available for an additional fee, with pricing dependent on the product(s) requested (please inquire).
  • Optional photography services are available for an additional fee, with pricing dependent on the images requested (please inquire).
  • Optional alternative carrier materials include stainless steel, borosilicate glass, polypropylene, vinyl, textured ABS, or others upon request for an additional fee.
  • Optional alternative inoculum suspensions are available without additional soil (serum).

Data Analysis

  • Data will be calculated to determine the quantifiable bacterial/fungal burden in colony-forming units per carrier (CFU/carrier) remaining on each test carrier.
  • Data will be analyzed to determine the consistency between replicate carriers (sample size n=3).
  • 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 unexposed carriers.