Simulated-Use Polytetrafluorethylene Biofilm Model: Repeated Rounds of Complete Reprocessing Lead to Accumulation of Organic Debris and Viable Bacteria

Abstract

OBJECTIVE Biofilm has been implicated in bacterial persistence and survival after endoscope reprocessing. In this study, we assessed the impact of different methods of reprocessing on organic residues and viable bacteria after repeated rounds of biofilm formation when each was followed by full reprocessing. METHODS ATS-2015, an artificial test soil containing 5-8 Log10 colony-forming units (CFU) of Enterococcus faecalis and Pseudomonas aeruginosa, was used to form biofilm in polytetrafluroethylene channels overnight on 5 successive days. Each successive day, full pump-assisted cleaning using bristle brushes or pull-through devices in combination with enzymatic or nonenzymatic detergents followed by fully automated endoscope reprocessor disinfection using peracetic acid was performed. Residuals were visualized by scanning electron microscopy (SEM). Destructive testing was used to assess expected cutoffs for adenosine triphosphate (ATP; <200 relative light units), protein (<2 µg/cm2), and viable bacteria count (0 CFU). RESULTS Protein residuals were above 2 µg/cm2, but ATP residuals were <200 relative light units for all methods tested. Only when enzymatic cleaner was used for cleaning were there no viable bacteria detected after disinfection irrespective of whether bristle brushes or pull-through devices were used. SEM revealed that some residual debris remained after all reprocessing methods, but more residuals were detected when a nonenzymatic detergent was used. CONCLUSIONS Surviving E. faecalis and P. aeruginosa were only detected when the non-enzymatic detergent was used, emphasizing the importance of the detergent used for endoscope channel reprocessing. Preventing biofilm formation is critical because not all current reprocessing methods can reliably eliminate viable bacteria within the biofilm matrix. Infect Control Hosp Epidemiol 2017;38:1284-1290.

The polytetrafluoroethylene (PTFE) channel model of cyclic-buildup biofilm and traditional biofilm: The impact of friction, and detergent on cleaning and subsequent high-level disinfection

“…Subsequent research has shown that use of partial HLD combined with filter membrane concentration improved detection of low levels of viable bacteria in CBB. 27 In conclusion, our study provides further support for the importance of friction in the endoscope-channel cleaning process. Furthermore, we demonstrated that multispecies biofilm formed using a relevant organic test soil with repeated rounds of fixation provides a more stringent approach for cleaning validation.…”

“…The Pull Thru channel cleaner was more effective at removing the colored solution compared to the bristle brush. 26 Alfa et al (2017) 27 reported that the Pull Thru channel cleaner was more effective than a bristle brush at preventing accumulation of organisms and organic material. Our study showed no significant difference between removal of bacteria using the bristle brush versus the Pull Thru device, but this finding may be related to the difficulty in removing traditional biofilm once it has been allowed to form over many days.…”

Microbiologic assessment of flexible gastrointestinal endoscope reprocessing using a pump-assisted sampling technique: an investigation involving all endoscopy units in Tianjin, China

“…24 A recent study reported that preventing biofilm formation is critical because not all current reprocessing methods can reliably eliminate viable bacteria within the biofilm matrix. 25 Furthermore, others have reported that biofilm presents unique challenges, both in terms of medical device reprocessing and infectious diseases. 26 This study had several limitations.…”

Turbulent fluid flow is a novel closed-system sample extraction method for flexible endoscope channels of various inner diameters

“…sterile reverse osmosis (sRO) water, neutralizing pharmacopeia diluent (NPD), buffer solutions, Tween containing fluids, various broth media) combined with brushing of some channels to provide friction (Beilenhoff et al 2006, Alfa et al 2017a, Gazdik et al 2016, FDA-CDC-ASM guideline 2018, Systchenko et al 2000, Rauwers et al 2017. Friction has been shown to be a critical factor to ensure optimal sample extraction from PTFE channels (Alfa et al 2017a) and has traditionally been achieved using a channel bristle brush or pull-through channel cleaners with a flush-brush-flush extraction process (Brock et al 2015, Alfa et al 2017b, FDA-CDC-ASM guideline 2018, Rauwers et al 2018). These bristle brushes and pull-through cleaners were originally designed to be used during the manual channel cleaning process.…”