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Clostridium difficile – Guidance and Methods for Antimicrobial Efficacy Testing

For Release: December 20, 2016

Updated January 19, 2017: The comment period has been extended to March 22, 2017.

EPA is announcing the availability for public comment of two proposed test methods and associated testing guidance for evaluating the effectiveness of antimicrobial pesticides against Clostridium difficile (C. diff).

C. diff is an anaerobic, spore-forming bacterium and a frequent cause of hospital-acquired infections. EPA recognizes the potential public health implications of C. difficile and recommends specific laboratory methodologies to produce and store spores, apply the spores to a hard non-porous surface, and evaluate the effectiveness of antimicrobial products intended to treat these surfaces.

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), 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. This announcement updates the guidance issued in June 2014.

EPA is soliciting comments on the clarity of the standard operating procedures and the regulatory guidance. Comments will be accepted for 60 days (until February 20, 2017), at which point EPA will finalize the procedures and provide the revised methods for use. The methods, guidance and additional background documents are available in Docket EPA-HQ-OPP-2016- 0753 at