C. difficile does present a challenge given its ability to produce spores. These spores are not inactivated by many disinfectants commonly used in hospitals and can survive for up to five months in the environment. If there is evidence of an ongoing cluster of infections, an undesirably high endemic rate or outbreak of CDI, disinfection of surfaces using 1:10 dilution of sodium hypochlorite (liquid bleach) may lower contamination of the environment with C. difficile spores. Bleach, however, is not a particularly effective agent for cleaning environmental surfaces, so a detergent to remove soil before attempting disinfection is still recommended. There is some evidence that bleach and other oxidizing disinfectants can inactivate spores, however both contact time and concentration are important parameters to follow.

Cleaning with bleach, using household measurement terms

The glossary in the CDC guidelines provides bleach dilutions using household measurement terms and equivalent parts per million (ppm) that can be used to translate recommendations for use in the patient care setting for environmental decontamination after cleaning, e.g., for Clostridium difficile. The Safety Institute has expanded the information to include the use of chlorine bleach as a sanitizing agent in dietary settings consistent with EPA U.S Govt. regulations (21 CFR Part 178).

Bleach
Solution
Dilution
Exact
Chlorine
(ppm)
Dilution
approximate
Household
(ppm)
Approximate
Application
5.25% – 6.15% Concentrate 52,500 – 61,500 Concentrate 52,500 – 61,500 *Patient Care
5.25% – 6.15% 1:10 5,250 – 6,150 1.5 cups / 1 gallon ~6000 *Patient Care
5.25% – 6.15% 1:100 525-615 0.25 cup / 1 gallon ~600 *Patient Care
5.25% 1:200 263 1 tablespoon / 1 gallon <200   Dietary
5.25% – 6.15% 1:1000 53-62 1 teaspoon / 1 gallon ~50   Dietary

* See specific recommendations in the CDC Guideline for Disinfection and Sterilization in Healthcare Facilities, (2008)