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Biofilm removal by medical device cleaners: comparison of two bioreactor detection assays
1Department of Plastic and Maxillofacial Surgery, South Western Sydney Clinical School, University of NSW and SIRG, Sydney, Australia.
Abstract:
Currently there are no standards for testing efficacy of medical device cleaners. With fears of prion transmission, residual protein on medical devices needs to be minimised. A bioreactor model was used to grow Pseudomonas aeruginosa biofilm on polytetrafluoroethylene coupons. The biofilm was subjected to various cleaners and residual biofilm was detected either by Crystal Violet assay (CrV) or a commercially available protein assay (PA) following hydrolysis of the biofilm. Percentage reduction of biofilm was compared with untreated controls in three independent tests. There was no significant difference in percentage biofilm reduction irrespective of whether the CrV or PA was used to detect residual biofilm. Processing of coupons attached to the bioreactor rod and position of coupon within the rod had no significant effect on cleaning efficiency or detection of residual biofilm. Both within-run and between-run variation was very low for good cleaners such as 10g/L NaOH, Zen, and 3M Rapid Multi-Enzyme Cleaner (RMEC) 70500 but was higher for poor cleaners such as Tween 20 which removed less than 20% of the biofilm. Confocal microscopy and electron microscopy provided visual confirmation of the assay results. We propose that this method is suitable as a test method for evaluating the efficacy of surgical instrument cleaners in removing biofilm, as both within-run and between-run variation was low, detection of residual biofilm can be done using either CrV or PA, and the apparatus is easy to use, cheap and readily available.
Insights
This study introduces a reliable bioreactor method for testing medical device cleaner efficacy. The proposed method effectively quantifies residual biofilm, ensuring safer medical instrument reprocessing.
Area of Science:
- Biomedical Engineering
- Microbiology
- Materials Science
Background:
- Lack of standardized methods for testing medical device cleaner efficacy.
- Concerns regarding prion transmission necessitate minimizing residual protein on medical devices.
Purpose of the Study:
- To develop and validate a bioreactor model for assessing the efficacy of medical device cleaners.
- To compare Crystal Violet assay (CrV) and protein assay (PA) for residual biofilm detection.
Main Methods:
- Utilized a bioreactor to cultivate Pseudomonas aeruginosa biofilm on polytetrafluoroethylene coupons.
- Subjected biofilms to various cleaners and quantified residual biofilm using CrV and PA.
- Analyzed the impact of coupon processing and position on cleaning efficiency.
Main Results:
- No significant difference was observed between CrV and PA for detecting residual biofilm.
- Low within-run and between-run variation was found for effective cleaners (e.g., NaOH, RMEC 70500).
- Confocal and electron microscopy confirmed assay results, with poor cleaners showing <20% biofilm reduction.
Conclusions:
- The proposed bioreactor method is suitable for evaluating surgical instrument cleaner efficacy.
- The method demonstrates low variability, versatile detection options (CrV or PA), and is practical for laboratory use.
