Written by: Crystal Booth, M.M.- Regional Manager, Southeast USA, PSC Biotech™

Disinfectant efficacy testing is a means to measure the effectiveness of disinfectants that are employed to clean, sanitize, or disinfect surfaces. It plays an important role in controlling microbial contamination on surfaces. 

There are many regulations and guidance documents that discuss disinfectant efficacy testing and the topic is fair game in regulatory audits. There three well-known versions of the test, the use-dilution test, surfaces challenge tests, and in-situ field studies.  

The use-dilution test is also known as in-suspension studies. It is a quick screen that can be performed with new environmental isolates that are found in environmental monitoring. It is not a replacement for the surface challenge test. Simply, you inoculate approximately 1 X 106 CFU of the microorganism into 9.9 mL of the working disinfectant solution.  After the allotted contact time has expired, you process the solution and test for viable microorganisms.

The surface challenge test, also known as the coupons study or the carrier surface study, is the most common method for testing disinfectant efficacy. It involves using coupons made of the materials that are the surfaces in your facility. You should use a risk-based approach to select the worst-case surface coupons, microorganisms, disinfectant working solution concentration, and wet-contact times for the test. You inoculate the coupon surfaces with microorganisms, dry the surfaces gently, and then apply the disinfectant as it would be in the manufacturing environment. After the allotted contact time expires, you process the coupons are processed to test for any remaining microorganisms.

The in-situ field study, also known as statistical comparison tests, is performed in the manufacturing facility, most commonly before and after an area start-up or before and after cleaning and disinfection during normal operations. Simply, environmental monitoring (EM) is performed in the “as is” or “dirty environment”, the area is cleaned, and then the EM is performed again. The results are compared to determine the decrease in microbial numbers.

The best way to present disinfectant efficacy testing to regulators is to be organized and have your data ready in a neat package. Establishing a compliant disinfectant efficacy testing package aids in providing clear documentation that the disinfectants employed in a facility have been analyzed correctly. 

PSC Biotech™ can help ensure your disinfectant efficacy studies as well as your facility and procedures are ready for a regulatory audit. Our professional services team can perform cGMP audits of your facility, including your disinfectant efficacy testing. We can help you prepare to present and discuss your data with confidence during regulatory audits of your facility. Contact us today!

PSC Biotech™ and BIO Business Solutions® are hosting a joint webinar on the Fundamentals of Disinfectant Efficacy Testing. Click the button below to register!