Residual moisture and waterborne pathogens inside flexible endoscopes: Evidence from a multisite study of endoscope drying effectiveness

Am J Infect Control. 2018 Jun;46(6):689-696. doi: 10.1016/j.ajic.2018.03.002. Epub 2018 Mar 30.


Background: Endoscopy-associated infection transmission is frequently linked to inadequate reprocessing. Residual organic material and moisture may foster biofilm development inside endoscopes. This study evaluated the effectiveness of endoscope drying and storage methods and assessed associations between retained moisture and contamination.

Methods: Endoscope reprocessing, drying, and storage practices were assessed at 3 hospitals. Researchers performed visual examinations and tests to detect fluid and contamination on patient-ready endoscopes.

Results: Fluid was detected in 22 of 45 (49%) endoscopes. Prevalence of moisture varied significantly by site (5%; 83%; 85%; P < .001). High adenosine triphosphate levels were found in 22% of endoscopes, and microbial growth was detected in 71% of endoscopes. Stenotrophomonas maltophilia, Citrobacter freundii, and Lecanicillium lecanii/Verticillium dahliae were found. Retained fluid was associated with significantly higher adenosine triphosphate levels (P < .01). Reprocessing and drying practices conformed with guidelines at 1 site and were substandard at 2 sites. Damaged endoscopes were in use at all sites.

Conclusions: Inadequate reprocessing and insufficient drying contributed to retained fluid and contamination found during this multisite study. More effective methods of endoscope reprocessing, drying, and maintenance are needed to prevent the retention of fluid, organic material, and bioburden that could cause patient illness or injury.

Keywords: Adenosine triphosphate; Contamination; Endoscope; Infection; Reprocessing; Stenotrophomonas maltophilia.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / analysis*
  • Bacteria / isolation & purification*
  • Decontamination / methods*
  • Desiccation / methods*
  • Disease Transmission, Infectious / prevention & control
  • Endoscopes / microbiology*
  • Equipment Reuse
  • Fungi / isolation & purification*
  • Prevalence
  • Prospective Studies
  • Water / analysis*


  • Water
  • Adenosine Triphosphate