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The development of a new three-step protocol to determine the efficacy of disinfectant wipes on surfaces contaminated
G J Williams1, S P Denyer, I K Hosein
1Welsh School of Pharmacy, Cardiff University, UK. Williamsgj3@cf.ac.uk
Abstract:
We developed a three-step protocol to quantify the efficacy of disinfectant wipes, their ability to remove and prevent microbial transfer from surfaces and their overall antimicrobial activity. Meticillin-resistant (MRSA) or -susceptible (MSSA) Staphylococcus aureus (6-7 log(10)cfu) were inoculated onto stainless steel discs with or without organic load and dried. Grapefruit extract-containing test wipes and unmedicated control wipes were used. In step 1, wipes were mechanically rotated against surfaces for 10s at 60rpm, exerting a weight of 100+/-5g. Bacterial removal was assessed by transferring the steel discs to neutraliser, resuspending and counting remaining bacteria. In step 2, bacterial transfer from wipes was assessed by eight consecutive mechanical adpression transfers to agar/neutraliser plates. Step 3 was the measurement of antimicrobial activity by direct inoculation of the wipes for 10s followed by neutralisation and enumeration. Test wipes achieved a significantly higher bacterial cell removal than control wipes on all surfaces (P<0.05). The low bactericidal activity of the wipes (<1 log(10) reduction when directly inoculated) and the subsequent survival of bacteria on the wipes, however, led to repeated microbial transfer when initially high contamination levels were present. There were no differences between MRSA and MSSA in removal, transfer or antimicrobial activity. The three-step method is a useful tool for developing future guidelines to assess the ability of wipes to disinfect surfaces.
Insights
This study presents a new three-step method to test disinfectant wipes' effectiveness. While test wipes removed more bacteria than controls, their limited antimicrobial activity allowed for repeated microbial transfer, highlighting areas for improvement in wipe development.
Area of Science:
- Microbiology
- Infectious Diseases
- Surface Disinfection
Background:
- Disinfectant wipes are crucial for infection control.
- Quantifying wipe efficacy requires standardized, multi-faceted assessment methods.
- Understanding bacterial removal, transfer, and inactivation is key to evaluating wipe performance.
Purpose of the Study:
- To develop and validate a three-step protocol for quantifying disinfectant wipe efficacy.
- To assess bacterial removal, microbial transfer, and antimicrobial activity of wipes.
- To evaluate the performance of grapefruit extract-containing wipes against Staphylococcus aureus.
Main Methods:
- Developed a three-step protocol involving mechanical rotation, bacterial transfer assessment, and direct antimicrobial activity measurement.
- Used Meticillin-resistant (MRSA) and -susceptible (MSSA) Staphylococcus aureus inoculated on stainless steel discs with or without organic load.
- Compared grapefruit extract-containing test wipes against unmedicated control wipes.
Main Results:
- Test wipes demonstrated significantly higher bacterial cell removal compared to control wipes (P<0.05).
- Wipes exhibited limited bactericidal activity (<1 log(10) reduction) and allowed for repeated microbial transfer.
- No significant differences were observed between MRSA and MSSA in removal, transfer, or antimicrobial activity.
Conclusions:
- The developed three-step method provides a comprehensive tool for assessing disinfectant wipe efficacy.
- Wipe efficacy is influenced by both bacterial removal and the wipe's inherent antimicrobial activity.
- Further development is needed to enhance the antimicrobial capacity of wipes to prevent secondary microbial transfer.
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