Disinfectant testing criteria for Clostridium difficile

Abstract

Introduction: The efficacy of disinfectants and disinfectant wipes against the spore forming Clostridium difficile (C difficile) is important to Infection Preventionists (IPs). There are variety of test methods for assessing disinfectant efficacy against C difficile and contact time claims are dependent on which test method is applied. The guidelines for Therapeutic Goods Order 54 (TGO54) do not specify a particular test for environmental disinfectants thus allowing manufacturers to select the method that provides the lowest contact time without improving underlying efficacy. This study examines presents results using various test methods for C difficile and other anaerobic spores using various standardised disinfectant active materials. Methods: Disinfectant testing using internationally recognised test methods were conducted against C difficile and other spore forming bacteria. Test methods including EN 13704, ASTM E2197 and suspension based methods outlined in the Guidelines for TGO54 were assessed. The suspension tests included both vegetative and spore enriched suspensions as well as the USA EPA method with spores dried onto carriers. Other variables included the organic and inorganic soils. Results: Differences in the test results are shown with a standardised concentration of disinfectant molecules including PAA and chlorine. The contact time required to meet the requirements of each test protocol was observed from 30 seconds to 20 minutes. Conclusion: Different test methods produce starkly different indications on efficacy again C difficile and anaerobic spores generally. IPs require more information than simply the “kill time” to accurately assess the likely in-situ performance of disinfectants or disinfectant wipes.