The Clorox Company''s Ultra Clorox® Germicidal Bleach is the first and only product to obtain federal EPA registration for killing Clostridium difficle (C. diff) spores on hard, non-porous surfaces. Ultra Clorox Germicidal Bleach is a registered disinfectant for use in all 50 states. C. diff spores can persist in the environment for many months and are highly resistant to many disinfecting formulations, until now.