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

Abstract

IntroductionSimulated-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 methodsBBF 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.ResultsDespite 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 conclusionWe 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.

Evaluation of an overnight non-culture test for detection of viable Gram-negative bacteria in endoscope channels

“…Our previous data showed that for 6639 CFU/mL of P. aeruginosa extracted from biofilm, there was only 1 RLU by the ATP test 9 . Furthermore, it took 7,424,795 CFU/mL extracted from biofilm to generate 1 μg/mL protein 9 .…”

“…Furthermore, it took 7,424,795 CFU/mL extracted from biofilm to generate 1 μg/mL protein 9 . These data demonstrated that although rapid ATP and rapid protein testing are very useful for monitoring manual cleaning compliance, they are very insensitive and cannot act as a substitute for culture post-HLD 2 10 27 29 Unlike rapid ATP and protein testing that do not detect low levels of viable bacteria 9 23 25 26 27 29 the RN test was sensitive enough to reliably detect nine of nine suspension tests when there were ≥ 10 CFU of viable E. coli and P. aeruginosa in the 0.5-mL sample tested. This is an excellent limit of detection but it must be borne in mind that all the current guidelines for interpretation of endoscope cultures 8 18 19 indicate that even 1 CFU per channel of a Gram-negative bacteria is considered unacceptable.…”

“…Instead of being able to use an endoscope multiple times each day, with the quarantine process, it can only be used for one procedure every 2 to 3 days (depending on how long the culture results take). Culture of endoscopes is also fraught with additional standardization issues such as the sample collection method used (i. e. type of friction, type of extraction fluid, use of neutralizer) 9 10 11 12 13 and the culture protocol used (i. e. concentration of sample, culture media and duration of incubation) affect the sensitivity of cultures 9 10 11 12 13 14 15 16 17 . Although culture is recommended in many countries as a monitoring tool for endoscope reprocessing, 11 18 19 it is not currently recommended in United States guidelines 20 21 22 and there is evidence that there can be false-negative culture results 3 23 .…”

Probenahme zur hygienisch-mikrobiologischen Überprüfung flexibler Endoskope – aktuelle Empfehlungen

“…Das Ablösen von Biofilmen, z. B. bei Spülproben, hängt vor allem von den hierbei erzeugten Scherkräften ab [35]. Hierzu liegen bis jetzt für Endoskope keine Untersuchungen vor.…”

Elevating the standard of endoscope processing: Terminal sterilization of duodenoscopes using a hydrogen peroxide–ozone sterilizer

“…The use of a flush-only method for the channels is recognized as a potential limitation compared with use of a flush-brush-flush method. A study by Alfa et al, published in 2017, 63 stated that a flush-only method with the use of a tensioactive agent such as Tween 80 seemed less effective than a flush-brush-flush method and that the potential role of such agents in terms of sample extraction efficiency from endoscope channels needed to be further evaluated. Also, a study by Alfa et al published in 2017 64 stated that the use of a flush-brush-flush method improved recovery of bacteria in biofilms.…”