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Pesticide News Story: Guidance for Evaluating Efficacy of Clostridium difficile Spores
For Release: March 18, 2009
Clostridium difficile (C. difficile) is a microorganism that has been implicated as a cause of potentially dangerous diarrheal illness. In 2008 EPA reversed its decision to allow disinfectant product label claims for the vegetative form of the organism, C. difficile. This decision was made in light of current research demonstrating that the spore form is persistent on environmental surfaces and is implicated in the spread of diarrhea associated with C. difficile. In addition, products effective against only the vegetative form could spread the spores and increase the possibility of infection. Given this information, the Agency believes products with claims of efficacy against only the vegetative form of the organism pose unreasonable risks of harm to health and the environment. Registrants were contacted and required to eliminate label claims for this organism until sporicidal data against C. difficile is generated.
The Agency has posted interim guidance for efficacy testing to obtain the C. difficile sporicidal claim for hard non-porous surfaces. The guidance presents four standard test methods for evaluation of dilutable and ready-to-use liquids; as well as procedural details, product performance standards, and special label language. The guidance also outlines the procedure if registrants wish to test spray, towelette or foam products; or if another test method is desired. Agency scientists and regulators are continually working to improve knowledge in this area and are confident that this interim approach will serve to educate registrants on testing against C. difficile that reflects real-world challenges, and will allow effective products to enter the market and address rising numbers of C. difficile-associated infections. A copy of the guidance is available on the Web site.