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Sterile Reverse Osmosis Water Combined with Friction Are Optimal for Channel and Lever Cavity Sample Collection of Flexible Duodenoscopes

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      Abstract

      Introduction

      Simulated-use buildup biofilm (BBF) model was used to assess various extraction fluids and friction methods to determine the optimal sample collection method for polytetrafluorethylene channels. In addition, simulated-use testing was performed for the channel and lever cavity of duodenoscopes.

      Materials and methods

      BBF was formed in polytetrafluorethylene channels using Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. Sterile reverse osmosis (RO) water, and phosphate-buffered saline with and without Tween80 as well as two neutralizing broths (Letheen and Dey–Engley) were each assessed with and without friction. Neutralizer was added immediately after sample collection and samples concentrated using centrifugation. Simulated-use testing was done using TJF-Q180V and JF-140F Olympus duodenoscopes.

      Results

      Despite variability in the bacterial CFU in the BBF model, none of the extraction fluids tested were significantly better than RO. Borescope examination showed far less residual material when friction was part of the extraction protocol. The RO for flush-brush-flush (FBF) extraction provided significantly better recovery of E. coli ( p = 0.02) from duodenoscope lever cavities compared to the CDC flush method.

      Discussion and conclusion

      We recommend RO with friction for FBF extraction of the channel and lever cavity of duodenoscopes. Neutralizer and sample concentration optimize recovery of viable bacteria on culture.

      Related collections

      Most cited references 24

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      The importance of the viable but non-culturable state in human bacterial pathogens

      Many bacterial species have been found to exist in a viable but non-culturable (VBNC) state since its discovery in 1982. VBNC cells are characterized by a loss of culturability on routine agar, which impairs their detection by conventional plate count techniques. This leads to an underestimation of total viable cells in environmental or clinical samples, and thus poses a risk to public health. In this review, we present recent findings on the VBNC state of human bacterial pathogens. The characteristics of VBNC cells, including the similarities and differences to viable, culturable cells and dead cells, and different detection methods are discussed. Exposure to various stresses can induce the VBNC state, and VBNC cells may be resuscitated back to culturable cells under suitable stimuli. The conditions that trigger the induction of the VBNC state and resuscitation from it are summarized and the mechanisms underlying these two processes are discussed. Last but not least, the significance of VBNC cells and their potential influence on human health are also reviewed.
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        A prospective study of the efficacy of routine decontamination for gastrointestinal endoscopes and the risk factors for failure.

        Patient-ready endoscopes were monitored over an 80-week period to determine the efficacy of decontamination procedures in a busy endoscopy center. Decontamination failure was related to patient and procedural parameters. Samples from patient-ready endoscopes were cultured aerobically and anaerobically and subjected to polymerase chain reaction (PCR) to detect hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV. PCR to detect coliforms from 109 culture negative washes was used as a surrogate marker for biofilm in endoscopes. PCR was used to detect the presence of Helicobactor pylori in endoscopes used on infected patients. Procedural information such as biopsy retrieval, endoscope number, diagnosis, attending personnel, and decontamination system procedures was collected. Gastroscopes (n = 1,376) and colonoscopes (n = 987) were equally contaminated (1.8% vs 1.9%, respectively) with low numbers of organisms commonly isolated from the nasopharynx and/or feces. Only 1 wash contained viral nucleic acid (HCV). There was a significant correlation (P < .001) between the number of times a patient-ready endoscope was contaminated and its frequency of use. Colonoscopes used on patients with gastrointestinal disease were significantly more likely to remain contaminated through the decontamination process (P < .05). All other patient, staff, and decontamination system parameters remained not statistically significant. Coliform DNA was detected in 40% of culture-negative washes collected from patient-ready endoscopes, suggesting the presence of biofilm. No H pylori DNA was detected. Recommended decontamination procedures do not entirely eliminate persistence of low numbers of organisms on a few endoscopes, but this is unlikely to cause serious consequences in patients. Bacterial biofilm is difficult to remove and may explain this low-level persistence.
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          Assessment on experimental bacterial biofilms and in clinical practice of the efficacy of sampling solutions for microbiological testing of endoscopes.

          Opinions differ on the value of microbiological testing of endoscopes, which varies according to the technique used. We compared the efficacy on bacterial biofilms of sampling solutions used for the surveillance of the contamination of endoscope channels. To compare efficacy, we used an experimental model of a 48-h Pseudomonas biofilm grown on endoscope internal tubing. Sampling of this experimental biofilm was performed with a Tween 80-lecithin-based solution, saline, and sterile water. We also performed a randomized prospective study during routine clinical practice in our hospital sampling randomly with two different solutions the endoscopes after reprocessing. Biofilm recovery expressed as a logarithmic ratio of bacteria recovered on bacteria initially present in biofilm was significantly more effective with the Tween 80-lecithin-based solution than with saline solution (P = 0.002) and sterile water (P = 0.002). There was no significant difference between saline and sterile water. In the randomized clinical study, the rates of endoscopes that were contaminated with the Tween 80-lecithin-based sampling solution and the saline were 8/25 and 1/25, respectively (P = 0.02), and the mean numbers of bacteria recovered were 281 and 19 CFU/100 ml (P = 0.001), respectively. In conclusion, the efficiency and therefore the value of the monitoring of endoscope reprocessing by microbiological cultures is dependent on the sampling solutions used. A sampling solution with a tensioactive action is more efficient than saline in detecting biofilm contamination of endoscopes.
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            Author and article information

            Affiliations
            1St. Boniface Research Centre , Winnipeg, MB, Canada
            2Department of Medical Microbiology, University of Manitoba , Winnipeg, MB, Canada
            3Department of Internal Medicine, University of Manitoba , Winnipeg, MB, Canada
            4Winnipeg Regional Health Authority , Winnipeg, MB, Canada
            5St. Boniface Hospital , Winnipeg, MB, Canada
            Author notes

            Edited by: Arun Chaudhury, GIM Foundation, United States

            Reviewed by: Madhukar Reddy Kasarla, Parkway Surgical and Cardiovascular Hospital, United States; Sunil Kumar, Neshoba County General Hospital and Nursing Home, United States; Sudheer Reddy Koyagura, Northwest Medical Center, United States

            *Correspondence: Michelle J. Alfa, malfa@ 123456sbrc.ca

            Specialty section: This article was submitted to Gastroenterology, a section of the journal Frontiers in Medicine

            Contributors
            Journal
            Front Med (Lausanne)
            Front Med (Lausanne)
            Front. Med.
            Frontiers in Medicine
            Frontiers Media S.A.
            2296-858X
            07 November 2017
            2017
            : 4
            5681997
            10.3389/fmed.2017.00191
            Copyright © 2017 Alfa, Singh, Nugent, Duerksen, Schultz, Reidy, DeGagne and Olson.

            This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

            Counts
            Figures: 3, Tables: 3, Equations: 0, References: 28, Pages: 9, Words: 6632
            Funding
            Funded by: American Society for Gastrointestinal Endoscopy 10.13039/100001947
            Award ID: 2015 Duodenoscope Infection Control Research Award from ASGE
            Categories
            Medicine
            Original Research

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