Potential testing of reprocessing procedures by real-time polymerase chain reaction: A multicenter study of colonoscopy devices

Am J Infect Control. 2018 Feb;46(2):159-164. doi: 10.1016/j.ajic.2017.08.008. Epub 2017 Sep 25.


Background: Reprocessing of endoscopes is key to preventing cross-infection after colonoscopy. Culture-based methods are recommended for monitoring, but alternative and rapid approaches are needed to improve surveillance and reduce turnover times. A molecular strategy based on detection of residual traces from gut microbiota was developed and tested using a multicenter survey.

Methods: A simplified sampling and DNA extraction protocol using nylon-tipped flocked swabs was optimized. A multiplex real-time polymerase chain reaction (PCR) test was developed that targeted 6 bacteria genes that were amplified in 3 mixes. The method was validated by interlaboratory tests involving 5 reference laboratories. Colonoscopy devices (n = 111) were sampled in 10 Italian hospitals. Culture-based microbiology and metagenomic tests were performed to verify PCR data.

Results: The sampling method was easily applied in all 10 endoscopy units and the optimized DNA extraction and amplification protocol was successfully performed by all of the involved laboratories. This PCR-based method allowed identification of both contaminated (n = 59) and fully reprocessed endoscopes (n = 52) with high sensibility (98%) and specificity (98%), within 3-4 hours, in contrast to the 24-72 hours needed for a classic microbiology test. Results were confirmed by next-generation sequencing and classic microbiology.

Conclusions: A novel approach for monitoring reprocessing of colonoscopy devices was developed and successfully applied in a multicenter survey. The general principle of tracing biological fluids through microflora DNA amplification was successfully applied and may represent a promising approach for hospital hygiene.

Keywords: Flocked swab sampling; Health care-associated infections; Sanitation; Surveillance; mfDNA.

Publication types

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

MeSH terms

  • Colonoscopes / microbiology*
  • DNA, Bacterial / genetics
  • DNA, Bacterial / isolation & purification*
  • Disinfection / standards*
  • Equipment Contamination / prevention & control*
  • Humans
  • Quality Assurance, Health Care
  • Real-Time Polymerase Chain Reaction / methods*


  • DNA, Bacterial