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Mimicking disinfection and drying of biofilms in contaminated endoscopes
J Kovaleva1, J E Degener, H C van der Mei
1Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. j.kovaleva@mmb.umcg.nl
Abstract:
The effects of peracetic acid-based (PAA) disinfectant with, and without, additional drying on Candida albicans, Candida parapsilosis, Pseudomonas aeruginosa and Stenotrophomonas maltophilia, isolated from contaminated flexible endoscopes, in single- and dual-species biofilms were studied. Biofilms were prepared in sterile tissue culture polystyrene 96-well microtitre plates and were quantified using the tetrazolium salt (MTT) reduction assay and by counting colony-forming yeasts and bacteria from 10-fold serial biofilm dilutions on agar plates. An in vitro biofilm model was applied to mimic the biofilm formation inside the endoscope channels and to imitate the disinfection and drying procedures used for reprocessing of flexible endoscopes. The PAA-based disinfectant was effective against bacteria and yeasts in the planktonic and biofilm states directly after treatment, but allowed regrowth of all biofilms if the drying procedure was skipped. No biofilm regrowth occurred in wells after a drying procedure in all single- and dual-species biofilms. Routine cleaning procedures do not remove biofilm reliably from endoscope channels if the accurate drying procedure is not applied. This may explain the failure of decontamination during endoscope reprocessing.
Insights
Drying flexible endoscopes after peracetic acid (PAA) disinfectant treatment is crucial. Skipping this step allows harmful Candida and Pseudomonas biofilms to regrow, compromising decontamination.
Area of Science:
- Microbiology
- Infection Control
- Medical Device Reprocessing
Background:
- Flexible endoscopes can harbor microbial biofilms, posing infection risks.
- Inadequate reprocessing may lead to persistent contamination and patient harm.
Purpose of the Study:
- To evaluate the efficacy of peracetic acid (PAA) disinfectant on Candida and Pseudomonas biofilms.
- To determine the impact of a drying step on PAA disinfectant effectiveness for endoscope reprocessing.
Main Methods:
- Studied single- and dual-species biofilms of Candida albicans, Candida parapsilosis, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia.
- Utilized an in vitro biofilm model in 96-well microtitre plates, mimicking endoscope channels.
- Quantified biofilm viability using MTT reduction assay and colony-forming unit counts.
Main Results:
- PAA disinfectant effectively reduced planktonic and biofilm microbes initially.
- Skipping the drying step after PAA treatment resulted in regrowth of all studied biofilms.
- Implementing a drying procedure prevented biofilm regrowth in all tested single- and dual-species biofilms.
Conclusions:
- The drying step is essential for complete eradication of microbial biofilms after PAA disinfection.
- Incomplete endoscope reprocessing, specifically omitting drying, can lead to disinfection failures.
- Adherence to accurate drying procedures is critical for reliable decontamination of flexible endoscopes.
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