Longitudinal assessment of reprocessing effectiveness for colonoscopes and gastroscopes: Results of visual inspections, biochemical markers, and microbial cultures

Am J Infect Control. 2017 Feb 1;45(2):e26-e33. doi: 10.1016/j.ajic.2016.10.017.


Background: Flexible endoscopes are currently reused following cleaning and high-level disinfection. Contamination has been found on endoscopes, and infections have been linked to gastrointestinal, respiratory, and urologic endoscopes.

Methods: This longitudinal study involved visual inspections with a borescope, microbial cultures, and biochemical tests for protein and adenosine triphosphate to identify endoscopes in need of further cleaning or maintenance. Three assessments were conducted over a 7-month period. Control group endoscopes reprocessed using customary practices were compared with intervention group endoscopes subjected to more rigorous reprocessing.

Results: At final assessment, all endoscopes (N = 20) had visible irregularities. Researchers observed fluid (95%), discoloration, and debris in channels. Of 12 (60%) endoscopes with microbial growth, 4 had no growth until after 48 hours. There were no significant differences in culture results by study group, assessment period, or endoscope type. Similar proportions of control and intervention endoscopes (~20%) exceeded postcleaning biochemical test benchmarks. Adenosine triphosphate levels were higher for gastroscopes than colonoscopes (P = .014). Eighty-five percent of endoscopes required repair due to findings.

Conclusions: More rigorous reprocessing was not consistently effective. Seven-day incubation allowed identification of slow-growing microbes. These findings bolster the need for routine visual inspection and cleaning verification tests recommended in new reprocessing guidelines.

Keywords: Adenosine triphosphate; Endoscope; Epidemiology.

MeSH terms

  • Adenosine Triphosphate / analysis
  • Biomarkers
  • Colonoscopes*
  • Decontamination / methods*
  • Disinfection / methods*
  • Equipment Contamination*
  • Equipment Reuse*
  • Gastroscopes*
  • Humans
  • Longitudinal Studies
  • Prospective Studies
  • Proteins / analysis


  • Biomarkers
  • Proteins
  • Adenosine Triphosphate