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Methods and Guidance for Testing the Efficacy of Antimicrobials against Spores of Clostridium difficile

For Release: September 29, 2017

EPA is announcing the availability of test methods for evaluating the efficacy of antimicrobial pesticides against Clostridum difficile as well as regulatory guidance for pesticidal claims for those products. These test methods and guidance provide a framework for registrants who seek to make a claim for antimicrobial pesticide products to control these spores on hard, non-porous surfaces. 

Under the Federal Insecticide, Fungicide, and Rodenticide Act, the registrant of an antimicrobial product with a public health claim is required to submit efficacy data to EPA in support of the product’s registration. 

Clostridium difficile is an anaerobic, spore-forming bacterium and a frequent cause of hospital-acquired infections. The spores survive on hard surfaces such as glass, metals, and plastics, which are commonly found in health-care settings. Antimicrobial pesticides are used to reduce the number of spores on environmental surfaces.

EPA solicited comments on the clarity of the test methods and the regulatory guidance in December 2016. The agency is also working with ASTM International, a standard-setting organization, on adoption of these test methods as official ASTM standards.

The agency’s response to comments and other documents associated with this action are available in docket EPA-HQ-OPP-2016-0753 at [] The methods and guidance are found at, MB-28 and MB-31.