Bacterial and Fungal Disinfectant Efficacy Studies

LexaMed assists pharmaceutical and medical device manufacturers by conducting in-vitro and in-situ disinfectant efficacy studies. Manufacturers must validate disinfectant regimens used in cleanrooms and other controlled areas to demonstrate efficacy of the disinfectants.   Disinfectant efficacy testing is conducted per several standards including AOAC Chapter 6 tests, ASTM E 2315, USP General Chapter 1072 and ASTM E 26140.  Typical studies use coupons constructed of surface materials found in the facility. Coupons are inoculated with ATTC traceable organisms as well as environmental isolates unique to the client’s manufacturing facility.  Application of the disinfectants to the coupons reflects the actual disinfectant application method used at the client facility.  The effectiveness of disinfecting solutions against organisms within a manufacturing facility is becoming an increasing area of concern to both manufacturers and regulatory agencies. Below is a brief description of a disinfectant efficacy study.

In-vitro Study (in Suspension):

  • Ready-to-Use solutions of each antimicrobial product are challenged with each organism in duplicate or triplicate test tubes. After a determined dwell period survivors are extracted and recovered for determination of a log10 reduction value.
  • The extraction method is validated for its neutralization efficacy against all solutions and organisms.

In-situ Study (with Surfaces):

  • Surface coupons are cleaned and sterilized to eliminate any possible background contamination.
  • The extraction method for each organism from each surface type is qualified demonstrating an acceptable efficiency.
  • The recovery and incubation method is validated for its neutralization efficacy using an un-inoculated coupon.  This is conducted for each organism and surface coupon combination.
  • Duplicate or triplicate coupons are inoculated with an organism challenge of not less than 105 CFU.  A coupon set is prepared, disinfected, and allowed to dwell for a period of time matching actual client use.
  • After the exposure period, each coupon is extracted for the surviving population using the qualified method.
  • Disinfectants are used near their expiration date if possible.

Example of a Test Matrix:

  • Antimicrobial Agent
  • Decon-Ahol (70% IPA)

    Hypo-Chlor (chlorine)

    Vesphene®

    Decon-Spore (peracetic acid)

    Steri-Perox (hydrogen peroxide)

  • Materials
    (tested with all agents)
  • Stainless Steel (316)

    Lexan (clear plexiglass)

    Wall (epoxy coated)

    Delrin (hard plastic)

    Nitrile (gloves)

  • Microorganisms
  • Pseudomonas aeruginosa

    Staphylococcus aureus

    Candida albicans

    Aspergillus brasiliensis

    Bacillus subtilis

    Environmental Isolate #1, Bacillus sp.

    Environmental Isolate # 2, Staphylococcus epidermidis

  • Time Challenges
  • 5 / 10 / 15 minutes for all organisms, surfaces, and solutions
  • Antimicrobial Agent
  • Decon-Ahol (70% IPA)

    Hypo-Chlor (chlorine)

    Vesphene®

    Decon-Spore (peracetic acid)

    Steri-Perox (hydrogen peroxide)

Xiao-qun Zeng

Xiao-qun Zeng

Senior Project Manager

Xiao is our resident subject matter expert in disinfectant efficacy studies. Feel free to contact Xiao with any questions via email at xzeng@lexamed.net.

Contact Xiao

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