ASTM E2197 Standard Quantitative Disk Carrier Test Method

Purpose of Test

The ASTM E2197 test method is a carrier-based test method used to evaluate liquid chemicals intended to inactivate vegetative bacteria, fungi, mycobacteria and bacterial spores. The method most often used to evaluate the efficacy of a product for hard surface disinfection against Clostridium difficile (“C. diff”) spores for registration with the U.S. EPA and Health Canada. In some cases, the method can be modified to evaluate single-use towelettes for efficacy as well.

Summary of Test

In this method, a series of stainless steel disks are inoculated with the test organism, commonly C. difficile spores. The carriers are desiccated and subsequently treated with a sample of the liquid disinfectant. After exposure, the carriers are neutralized and quantitatively assayed for surviving test organism. The resulting plates are incubated, the number of survivors is enumerated and a percent and log10 reduction is determined as compared to a population control. In the case of C. difficile, efficacy is demonstrated when a 99.9999% or 6 log10 reduction has been observed.