Microbial Validation/Verification

Pharmacopeia in the United States requires that the disinfectants used in facilities are proven to be effective. This requires the user to provide documentation that the cleaning agent(s) is effective on the hard surfaces present in the facility, as well as resident microrganisms.

USP provides guidance on the types and strains of organisms used for this study and they can be obtained through specific culture collection agencies. Resident organisms are usually obtained through environmental monitoring or product contaminants. The organisms are identified and a culture is prepared accordingly.

The test consists of inoculating the panels with a high population titer of each organism, applying the disinfectant for the required time and swabbing to evaluate the reduction of organisms in a logarithmic value. Studies also need to be completed to show that the compounds of interest have been sufficiently neutralized and that growth is not inhibited.

Items to consider when conducting a study:

  • Expiry dating of the cleaning agents – A study may be done at, close to, or after the expiration date of the agent to verify the cleaning agents are still effective.
  • Reduced contact time – This will verify if the agent is still effective if the established contact time was not met.
  • Improper dilution of the cleaning agent– This study will determine whether the agent is capable of reducing the bioburden if it is not prepared correctly.

If the study shows that the agent was not effective in reducing all microrganisms to an acceptable level, the user must modify the procedure and repeat the study. This can be accomplished in several ways, for instance, increasing the contact time or changing the agents.

After the method has been validated, the user will develop a schedule to sample the equipment on a routine basis to verify that the agents and methods are still acceptable in reducing the bioburden.

Read more about considerations when performing microbial cleaning validation.