This test method describes a procedure for preparing a spore suspension of C. difficile strain ATCC 43598 that meets specific criteria necessary for efficacy testing of antimicrobials designed to eliminate C. difficile contamination from environmental surfaces. The acceptability criteria for the spore suspension are: (1) a viability titer of >8 log₁₀/mL, (2) purity of ≥95 %, and (3) that spores be resistant to 10 min of exposure to 2.5 M HCl.

1.1 This test method is for producing C. difficile spores to evaluate antimicrobial formulations for their sporicidal activity.

1.2 It is the responsibility of the investigator to determine whether Good Laboratory Practices (GLP) are required and to follow them when appropriate.

1.3 This standard may involve hazardous materials, chemicals, and microorganisms and should be performed only by persons with formal training in microbiology.

1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.