Disinfectant Efficacy Testing

Disinfection and cleaning of critical areas is a key component to successful control of these environments. In addition to validating the cleaning process, the disinfectants and antiseptics implemented should be qualified. This should include a review of vendor certificates and data, but typically also requires actual testing, such as use-dilution tests (e.g. AOAC 955.14, 955.15, 964.02), which verify the dilution of disinfectants against specified microbial strains, as well as the following: Sporicidal Activity of Disinfectants (AOAC 966.04), Germicidal Spray products tests, confirmatory tuberculocidal activity tests, and fungicidal activity.

A sanitizer or disinfectant efficacy study should also include simulation studies, hard surface tests, and tests under nominal conditions/procedures. Disinfectant validation may also include in vitro tests: Time Kill Study or suspension testing, Coupon or Carrier testing, Environmental monitoring, and in situ testing.

In designing a disinfectant efficacy validation or verification, the following are important considerations:

  • Surfaces present in the critical area, including different conditions or types of the same material, should be tested.
  • Each disinfectant, and dilution thereof, to be qualified should be challenged by a panel of representative organisms
  • This typically includes standard USP organisms: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis (spore), Candida albicans,  and Aspergillus brasiliensis.
  • The panel should also include environmental isolates from the critical area collected from environmental monitoring of the facility or critical area.
  • Contact time for each disinfectant
  • Expiration verification through the use of aged disinfectant preparations.
  • Neutralization of the disinfectant, e.g. suitability testing.
  • Recovery method evaluation or control
  • Cleaning process overview and validation: facility materials and environment, disinfectant preparation, cleaning procedure and contact time, facility surfaces, facility-specific bacteria and fungi.

Reference documents

AOAC 955.14, 955.15, 964.02

AOAC 966.04