Optimizing Sanitation and Disinfection Practices; Clostridioides Difficile Spores and Dry Surface Biofilms of Staphylococcus Aureus and Pseudomonas Aeruginosa as Models

Carine Ajua Nkemngong, Purdue University

Abstract

Pre-wetted disinfectant wipes are increasingly being used to help address the risk of healthcare associated infections (HAIs). However, HAIs are still a major problem in the US with Clostridioides difficile being the most common cause. Dry surface biofilms (DSB) are also major contributors to the HAI problem as they persist on dry environmental surfaces and are harder to kill than wet surface biofilms (WSB) and planktonic bacteria. Limited studies have explored the cross-contamination risk when using disinfectant wipes against C. difficile spores. Even fewer studies have attempted to develop in vitro models for establishing DSB of Staphylococcus aureus and Pseudomonas aeruginosa for disinfectant efficacy testing; as there is currently no official method. The objectives of this work were to (i) determine the cross-contamination risk that prewetted disinfectant towelettes may pose when challenged with C. difficile spores and to; (ii) develop an in vitro model of S. aureus and P. aeruginosaDSB for disinfectant efficacy testing. Methods: Disinfectant wipes were used to wipe a Formica sheet inoculated with C. difficilespores. After the wiping process, log10 CFU on previously uncontaminated pre-determined distances from the inoculation point and on used wipes were determined. In establishing the in vitro DSB model for disinfectant efficacy testing, WSB grown on glass coupons following EPA MLB SOP MB-19 were dehydrated to form DSB and viable bacteria recovered following EPA MLB SOP MB-20. Methods: Disinfectant wipes were used to wipe a Formica sheet inoculated with C. difficile spores. After the wiping process, log10 CFU on previously uncontaminated pre-determined distances from the inoculation point and on used wipes were determined. In establishing the in vitroDSB model for disinfectant efficacy testing, WSB grown on glass coupons following EPA MLB SOP MB-19 were dehydrated to form DSB and viable bacteria recovered following EPA MLB SOP MB-20. Results: Disinfectant wipes transferred C. difficilespores from inoculated surfaces to previously uncontaminated surfaces with hydrogen peroxide (HP) disinfectants being more sporicidal than the quaternary ammonium (QA) disinfectants. A minimum of six mean log10 density of DSB required for disinfectant efficacy against WSB were recovered per coupon through our DSB establishment model. Overall, QA plus alcohol, sodium dichloro-s-triazinetrione and HP products were more bactericidal against DSB than QA products.

Degree

Ph.D.

Advisors

Oliver, Purdue University.

Subject Area

Food Science|Medicine|Microbiology|Pathology

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