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

  • Michelle J. Alfa (a1) (a2), Harminder Singh (a3), Zoann Nugent (a3), Donald Duerksen (a3), Gale Schultz (a4), Carol Reidy (a5), Pat DeGagne (a1) and Nancy Olson (a1)...



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.


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).


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.


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


Corresponding author

Address correspondence to Dr Michelle J Alfa, St. Boniface Research Centre, 351 Tache Ave, Winnipeg, Manitoba, Canada, R2H 2A6 (


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

  • Michelle J. Alfa (a1) (a2), Harminder Singh (a3), Zoann Nugent (a3), Donald Duerksen (a3), Gale Schultz (a4), Carol Reidy (a5), Pat DeGagne (a1) and Nancy Olson (a1)...


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