Re-Use Stress Testing and Evaluation of Disinfectants

Purpose of Test

The U.S. FDA and Health Canada require that high-level disinfectants intended to be continuously reused in a clinical setting be evaluated for efficacy after the product has been subjected to simulated re-use procedures. The purpose of this method is to generate a product which has undergone simulated use and periodic bio-burden stressing. The method used to stress the test substance is based on the guidance set forth in the U.S. EPA Draft Pesticide Assessment Guidelines 91A.

Summary of Test

In this method, products are processed through a series bio-burden stressing procedures to generate a product which has undergone simulated-use. Commonly, these products are combined with an organic soil load and undergo daily simulated-use cycles by processing medical equipment into and out of the product multiple times. Bio-burden stressing is performed each day by transferring a specific amount of inoculated carriers containing vegetative and spore-forming bacteria into the product. The products are typically stressed on a daily basis for up to 28 days to simulate the length of time the product would be re-used in a clinical setting. The final product is then evaluated for high-level disinfection efficacy using the AOAC Use Dilution, AOAC Sporicidal method and AOAC Tuberculocidal method, among others.