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The Current Situation and Problems of Endoscope Cleanliness in Osaka University Hospital

Tomomi MITSUI1), Keigo KIMURA1), Masaki TAKASHINA2) and Isao NISHI1)
1)Laboratory for Clinical Investigation, Osaka University Hospital, 2)Central Supply and Sterilization Department, Osaka University Hospital


We routinely perform microbiological surveillance of endoscopes (upper gastrointestinal endoscopy, colonoscopy, and bronchoscopy) to monitor the quality of reprocessing procedures (cleanliness survey) at our facility. We perform bacterial stain and culture of samples obtained by flushing with sterile saline through biopsy channels of endoscopes that were stored after reprocessing in this survey. We describe the result of this cleanliness survey through 2008 to 2016.
The positivity rates in bacterial isolation for 9 years in upper gastrointestinal endoscopy and colonoscopy were 21.4% and 13.8%, respectively. The annual positivity rates in upper gastrointestinal endoscopy and colonoscopy were 0-44.0% and 0-29.2%, respectively, which considerably decreased after 2013. In the years when microorganisms were detected frequently, we found that identical endoscopes were repeatedly positive for any organisms. No organism was detected from bronchoscopy. For the culture-positive endoscopes, after repeating cleaning and disinfection process, we reexamined them. The overall positivity rates in upper gastrointestinal endoscopy and colonoscopy were 4.4% and 3.0%, respectively. The annual positivity rates in upper gastrointestinal endoscopy and colonoscopy were 0-12.5% and 0-8.3%, respectively. The microorganisms that were detected after reexamination were almost identical in species to those that were isolated before the repeated reprocessing process. In spite of our efforts to investigate the cause, a possible reason for the failure in disinfection was unapparent.
After 2013, the annual rates decreased. However, in some endoscopes, even after repeated cleaning and disinfection, occasionally, microorganisms were detected. It seems difficult to remove microorganisms completely from the biopsy channels of endoscopes by the current method of cleaning and disinfection. The cleanliness survey requires us to uncover the cause of endoscope contamination and to prevent endoscope-associated infection.

Key words:endoscope, cleanliness survey, infection control

e-mail: sakata@hp-lab.med.osaka-u.ac.jp

Received: November 9, 2017
Accepted: March 16, 2018

33 (4):123─129,2018

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