FORT LAUDERDALE, Florida — In a study that measured the cleanliness of endoscopes used at 5 hospitals across the United States, 3 of 20 flexible gastrointestinal endoscopes used for screening were found to harbor unacceptable levels of bacteria.

The finding was a surprise, lead author Marco Bommarito, PhD, from the infection prevention division at 3M, in St. Paul, Minnesota, told Medscape Medical News.

"The expectation that we would see no failures was perhaps a high benchmark, but clearly, we would like no endoscopes to fail a cleanliness rating," he said here at the Association for Professionals in Infection Control and Epidemiology (APIC) 2013 Annual Meeting.

Each year, 15 to 20 million reusable endoscopes are used to screen various components of the gastrointestinal tract.

After an endoscope is used, it is cleaned manually by a technician using an enzymatic cleaner and then soaked in a high-level disinfectant. The manual cleaning is vital to ensure that the disinfection process is effective, Dr. Bommarito explained.

Once manual cleaning is finished, the technician visually inspects the scope to make sure it is clean. However, contamination not visible to the naked eye can remain on the device.

In their study, Dr. Bommarito and colleagues analyzed 275 flexible endoscopes that were used for colonoscopies, gastroscopies, and duodenoscopies.

After the manual decontamination and disinfection process, the cleaning technicians flushed the scopes with sterile water. This water sample was then analyzed for adenosine triphosphate (ATP), which is a marker of biocontamination.

The amount of ATP was measured with a handheld luminometer. On the basis of previously published clinical data, a failure threshold was set at 200 relative light units. Any instrument with an ATP level above that threshold was identified as a manual cleaning failure.

Table. Manual Cleaning Failure Rate

Instrument Failure Rate, % Mean Relative Light Units
Duodenoscope (n = 30) 30 145
Gastroscope (n = 116) 24 86
Colonoscope (n = 129) 3 30


"Of the 38 steps in the cleaning process, only 8% are actually measured for effectiveness," Dr. Bommarito said. "We should probably be measuring more steps in the process," he noted, or find a way to make the cleaning process simpler and easier for technicians.

"The industry is trying to develop equipment that essentially automates a good portion of the process. But it's not going to happen overnight, and it's the kind of thing that may not be affordable for all institutions," he said.

In the meantime, closer inspection and more quality control of the manual part of the cleaning process would help, as would improved working conditions for the technicians who do the cleaning, Dr. Bommarito said.

"It's a labor-intensive job that is physically demanding, because you're standing there, essentially scrubbing this piece of equipment, doing multiple pieces for many hours. Looking at the human factors involved in manual cleaning might be very beneficial. Perhaps shortening the time technicians must work would help. In some cases, they are standing for 8 hours. Perhaps shifts could be shortened," he said.

It's a labor-intensive job that is physically demanding, because you're standing there, essentially scrubbing this piece of equipment.

Another problem is the pressure to get the scopes cleaned because patients are waiting for their procedures. "It might be a good idea to look at ways to alleviate that time pressure so that the technicians have more time to reprocess that scope in a less stressful way," he said.

Dr. Bommarito emphasized that these findings do not necessarily mean that patients are in danger of being infected.

"We were not trying to uncover negligence. All of these centers were very welcoming and wanted to learn more about how they were doing. Also, we just measured the amount of bio-organic contamination on the scope after the manual cleaning. That doesn't necessarily mean that the scope was not properly disinfected. What it says is that if you have a scope that has a higher amount of contamination prior to disinfection, your disinfection process may be impaired," he explained.

"We know that endoscopes are difficult to clean. They have very long and narrow lumens and are used to access highly contaminated areas of the body. The use of ATP to measure levels of residual contamination is a step in the right direction," said Marcia Patrick, RN, an infection preventionist from Tacoma, Washington, who was invited by Medscape Medical News to comment on the study.

"If a facility implements a system to measure ATP and things look good, and then tests a month later and things still look good, perhaps dirty scopes are not an issue. But 3 of 20, as they found in this study, is fairly high," said Patrick, who was not part of the study.

"I think ATP is a wonderful tool, and this is a valuable study."

Dr. Bommarito is an employee of 3M. Ms. Patrick has disclosed no relevant financial relationships.

Association for Professionals in Infection Control and Epidemiology (APIC) 2013 Annual Meeting: Abstract 40. Presented June 9, 2013.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.