August 12, 2015 — Colonoscopes and gastroscopes often remain contaminated with infection-causing microbes even after meticulous cleaning, according to a study published by the American Journal of Infection Control.
Earlier this year, the FDA warned that duodenoscopes with complex “elevator” channels in the tip are very hard to sterilize and can transmit infections even after following the manufacturer’s cleaning instructions.
Now, researchers are warning that simpler endoscopes also frequently remain contaminated after they are cleaned. About 9% of the scopes still had viable microbes after they were cleaned and dried.
The authors of the study warned that “current standards and practices may not be sufficient for detecting and removing all residual contamination.”
Those conclusions came after researchers observed cleaning activities at the Mayo Clinic in Rochester, Minnesota, where about 30,000 endoscopic procedures are performed every year.
After each procedure, the scopes are highly-contaminated with blood, mucous, bacteria, and microbes. Because the scopes are too delicate to be sterilized with heat, they must be manually scrubbed, washed with disinfectants, and dried. Even after labor-intensive cleaning, slimy layers of bacteria and yeast (called “biofilm”) can form inside the scope and resist disinfection.
Infection experts have been warning for years that many types of medical scopes can remain dirty after cleaning — but concerns were mostly ignored until earlier this year, when duodenoscopes were linked to several deadly outbreaks of antibiotic-resistant infections.