New Guidance for Transitioning to the Sterilization of Flexible Endoscopes A newly developed 3-tiered classification scheme based on the infection risk is discussed.

May 30, 2019 New guidance designed to help medical facilities considering replacing high-level disinfection with sterilization of flexible endoscopes, including duodenoscopes, has just been published.

This guidance is based on a newly developed scheme that proposes classifying flexible endoscopes into one of three groups, based on the device’s documented risk of remaining contaminated and transmitting carbapenem-resistant Enterobacteriaceae and related multidrug-resistant organisms to patients.

In 2012, endoscopy emerged as a recognized risk factor for the transmission of these “superbugs.” The mortality rate associated with these resistant infections, particularly for ill patients with a compromised immune system, can be as high as 50% or higher.

Examples of these superbugs, which health officials sometimes refer to them as “nightmarish” bacteria, include NDM-producing Escherichia coli, carbapenemase-producing Klebsiella pneumoniae and VIM-2-producing Pseudomonas aeruginosa.

This guidance’s three-tiered scheme is presented in the newly published white paper entitled, “What You Need to Know When Replacing Disinfection with Sterilization of Flexible Endoscopes” — click here to download a complete free copy.



Expert Consulting Services: LFM-Healthcare Solutions, LLC provides medical expertise and guidance for hospitalsmanufacturers and the public, specializing in healthcare-associated infections linked to medical equipment.



In February 2015, the FDA began publicizing the threat of duodenoscopes transmitting superbug infections. Today, public health officials continue to focus on this risk, and not only because of the high associated mortality rates.

Several outbreak investigations in the U.S. and Europe, since 2012, reported that the duodenoscope remained persistently contaminated with CRE, or a related resistant organism, despite the device being reportedly cleaned and disinfected correctly.

In several cases, replacing high-level disinfection with low-temperature sterilization was found to terminate the outbreak. Other measures implemented to prevent additional infections included removing the implicated duodenoscope from clinical use.

Posing even a potentially greater public health concern than CRE, the healthcare-associated transmission of colistin-resistant bacteria carrying the mcr-1 gene has been recently linked to duodenoscopes. These bacteria can be pan-resistant, and their infections virtually untreatable.

Carbapenems and colistin are two types of “last resort” antibiotics used to treat serious resistant infections in hospitalized patients.

“High concern organisms”

Revisiting the potential for duodenoscopes to transmit multidrug-resistant bacterial infections, a U.S. senator from Washington state wrote a letter earlier this month to each of the three manufacturers of duodenoscopes sold in the U.S. — Company 1, Company 2 and Company 3 — inquiring about newly collected post-market surveillance test data.

These test data suggest the rate of contamination with “high concern organisms” for certain models of reprocessed duodenoscopes was higher than previously reported.

The FDA defines such high concern organisms as “organisms that are more often associated with disease, such as E. coli and Pseudomonas aeruginosa.”

This same U.S. senator published a detailed report about the safety of duodenoscopes in January 2016 entitled, “Preventable Tragedies: Superbugs and How Ineffective Monitoring of Medical Device Safety Fails Patients.”

Up to a 5.4% contamination rate 

In December, the FDA provided some preliminary findings from these ongoing post-market studies, announcing a 3% contamination rate for these high concern organisms after reprocessing the duodenoscopes in the clinical setting according to the manufacturer’s instructions.

Almost three years earlier, the FDA required these three manufacturers, pursuant to a 522 Order issued in October 2015, to sample reprocessed duodenoscopes in the clinical setting “to learn more about issues that contribute to contamination.”

This order also required the manufacturers to perform a second human factors study “to assess whether trained hospital staff are following the reprocessing instructions.

Last month, the FDA provided an update for these surveillance studies, reporting that up to 5.4% of “all properly collected samples” tested positive for these high concern organisms — a contamination rate that the agency acknowledged was significantly higher than reported four months earlier, in December.

The FDA also acknowledged in this April update that these sampling studies were designed with the expectation that the total contamination rate for any one type of organism recovered from a reprocessed duodenoscope would be less than 1%, or near zero.

This new guidance’s three tiers

According to this newly published guidance, facilities may consider establishing a working group that discusses classifying, into the scheme’s first category, flexible endoscopes that pose the highest documented risk of transmitting CRE and related multidrug-resistant organisms despite reprocessing.

Facilities might reasonably assign duodenoscopes to this first group, called the “high risk” group, based on current published data and risk assessments.

Also placed into this first group might be other flexible endoscopes that are also generally complex in physical design and also may be prone to remaining contaminated following reprocessing and possibly exposing patients to these superbugs. Linear-array echo-endoscopes may be an example.

Both duodenoscopes and linear-array echo-endoscopes feature a forceps elevator mechanism that can pose challenges to effective reprocessing. This mechanism is used to adjust the angle and direction of endoscopic accessories, such as a guide wire or needle, during the procedure.

According to the FDA, the moving parts of the forceps elevator mechanism, at least for duodenoscopes, “contain microscopic, hard-to-reach crevices.” If not thoroughly cleaned and disinfected, the FDA notes, “tissue or fluid and residual bacteria from one patient may remain in device crevices of a duodenoscope, exposing subsequent patients to risk of infection.”

An “EBUS” endoscope, used to perform endobronchial ultrasound, might also be reasonably classified into this first category, due to it his device’s design and potential exposure risk.

Current infection-control guidelines in the U.S. recommend at least high-level disinfection for duodenoscopes, echo-endoscopes and other flexible endoscopes. These devices are classified as “semi-critical” because they contact mucous membranes or non-intact skin, but do not ordinarily penetrate sterile tissues (like “critical” devices).

To date, none of these guidelines requires sterilization of flexible endoscopes.

This newly published guidance recommends, however, that (when deemed feasible, practical and warranted) medical facilities consider sterilization of the endoscopes in this first group (consistent with the manufacturer’s instructions), particularly in the outbreak setting, to reduce the risk of persistently contaminated devices transmitting multidrug-resistant bacteria to patients.

Duodenoscopes are a type of flexible endoscope used to diagnose and treat disorders and diseases of the bile and pancreatic ducts during a procedure called endoscopic retrograde cholangiopancreatography, or ERCP.

Echo-endoscopes may be used during endoscopic ultrasound, or EUS, for imaging and to sample tissues of the gastrointestinal (GI) tract, among other therapeutic applications.

This new guidance — click here to download a free copy of the white paper — provides a table identifying several low-temperature technologies, cleared by the FDA, that may be used to sterilize certain flexible endoscopes.

FDA’s four “supplemental measures”

The safety of the high-level disinfection of flexible endoscopes in past years has been well documented. Investigations of an infection linked to an endoscope almost always attributed transmission to one or more identifiable reprocessing breaches — for example, failure to clean the endoscope correctly.

Reports since 2012, however, suggest that current recommended reprocessing practices may not always be sufficient to prevent transmissions of CRE and related multidrug-resistant bacteria during certain endoscopic procedures, especially ERCP.

In addition to the device’s complex physical design, factors that can adversely impact high-level disinfection, posing an increased risk of the flexible endoscope transmitting a superbug, include improper cleaning, delayed reprocessing, inadequate maintenance and faulty repairs, among others.

Moreover, some data suggest that while crucial, the flawless adherence to every one of a complex endoscope’s several cleaning and disinfection steps can be challenging.

In August 2015, the FDA recommended that healthcare facilities consider implementing at least one of four additional steps, or “supplement measures,” to help reduce the risk of reprocessed duodenoscopes remaining contaminated and transmitting multidrug-resistant bacteria to patients.

Sterilization is one of the FDA’s four recommended measures. The other three are use of a liquid chemical sterilant processing system, microbiological culturing and “repeat” high-level disinfection.

Encouraging sterilization, the FDA advised in this August notice that “[w]hen possible and practical, duodenoscopes should be sterilized due to the greater margin of safety provided by sterilization.”

In a separate document also published in 2015, the FDA similarly advised that users of semi-critical devices (such as flexible endoscopes including duodenoscopes) “should be instructed to thoroughly clean these devices and then reprocess them by sterilization.”

The FDA’s document provided the caveat that if the (semi-critical) device’s design does not permit sterilization, “then high level disinfection should be used.”

Download this new guidance white paper — “What You Need to Know When Replacing Disinfection with Sterilization of Flexible Endoscopes” — to learn into which of these three groups a facility might classify a bronchoscope, a gastroscope and a colonoscope.



Expert Consulting Services: LFM-Healthcare Solutions, LLC provides medical expertise for hospitalsmanufacturers and the public, specializing in healthcare-associated infections linked to medical equipment. Services include litigation support.



The scheme’s second group 

Endoscopes classified into the second group would be generally simpler in physical design, and would pose a lower documented relative risk of remaining contaminated with multidrug-resistant bacteria after disinfection, compared to those in the first group.

While sterilization would be ideal for all endoscopes, the facility may conclude, for endoscopes in this second group, that its immediate implementation is infeasible or otherwise not yet practical.

In this case, this new guidance suggests that facilities consider adopting and applying (as circumstances warrant) to the endoscopes classified into this second group at least one of the FDA’s other three aforementioned supplemental measures (published in August 2015 for duodenoscopes).

Sterilization of these endoscopes in this group, which may be called the “moderate risk” group, would then be phased in over time as it became more practical.

These safety measures would be implemented in addition to standard cleaning and high-level disinfection of the endoscope according to the manufacturer’s instructions. (The FDA has not, to date, recommended that these four supplemental measures be similarly applied to endoscopes other than duodenoscopes.)

Notably, this guidance’s proposed classification scheme is designed to be flexible, and can be adjusted and revised by each facility as clinical circumstances warrant and new safety data suggest.

No matter, if the facility cannot ensure that the endoscopes in this second group have been cleaned and disinfected correctly by trained staff, reprocessing not delayed, and the devices’ repairs and maintenance consistent with the manufacturer’s instructions and scheduling (along with satisfying a few other safety criteria), then the infection risk could be high.

Under these circumstances, this guidance suggests that the facility consider re-classifying the endoscopes into the scheme’s first group.

Cystoscopes might be a type of flexible endoscope that, if not in the first group, a facility might classify into this second group (assuming all of the aforementioned safety criteria are satisfied).

Download a complete copy of this new guidance entitled “What You Need to Know When Replacing Disinfection with Sterilization of Flexible Endoscopesto learn more about these safety criteria, and to identify other types of flexible endoscopes that a facility might classify into this second group.


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The scheme’s third group

The flexible endoscopes a facility might classify into this scheme’s third group would be documented to pose a low, or negligible, risk of transmitting CRE and related multidrug-resistant when cleaned and high-level disinfected (and maintained) according to the manufacturer’s instructions.

Published data would suggest that sterilization of the devices in this group, compared to their high-level disinfection, may not provide a significant reduction in the reported infection risk. This group may be reasonably called the “low risk” group.

As a safety precaution nonetheless, facilities may consider adopting and applying (as circumstances warrant) to the endoscopes in this third group at least one of the FDA’s other three aforementioned supplemental measures published in August 2015 (in addition to standard cleaning and high-level disinfection) — for example, disinfecting the endoscope twice before reuse.

This new guidance recognizes, however, that even for the endoscopes in this third group, sterilization may become appropriate or warranted in certain instances – for example, to terminate an identified outbreak, or if surveillance cultures suggest the reprocessed endoscope is persistently contaminated with CRE or a related multidrug-resistant organism.

A “TEE” probe, used to perform transesophageal echocardiography (TEE), might be an example of a device a facility places into this third group. More examples of flexible endoscopes that a facility might reasonably assign to this third group are provided in this newly published guidance document.

During TEE, a probe featuring an ultrasound transducer is threaded into the esophagus to provide images of the heart.



Expert Consulting Services, Case Reviews:  Click here to read about the services LFM-HCS Solutions, LLC offers hospitals, manufacturers and the public in response to a healthcare-associated infection involving reusable medical equipment.



Concluding remarks

For background, Spaulding’s scheme adopted by the Centers for Disease Control and Prevention (CDC) and others classifies medical devices as critical, semi-critical, and non-critical based on their use and general infection risk.

This new guidance suggests further classifying flexible endoscopes, which are semi-critical, based on their documented risk of remaining contaminated and transmitting CRE and related multidrug-resistant organisms despite reprocessing.

Ideally, the types of flexible endoscopes classified into each of this new guidance’s three groups would be standardized and the same for every facility, based on similar infection risk assessments.

But, because the resources, circumstances and capabilities to perform sterilization are not the same for every facility, one may place a certain flexible endoscope type in this first group, while another facility might assign the same endoscope type to another group.

Overtime, however, the endoscope types in each group would be expected to become standardized and no longer be facility-dependent.



Readers may find the following four articles published in “Discussions in Infection Control” to provide information helpful to a better understanding of this article’s discussion about classifying flexible endoscopes into one of three groups, based on the relative infection risk:

  1. A Colonoscope is Linked to Two Infections of the Nightmarish ‘CRE’ Superbug(January 2019)
  2. A Bronchoscope is Linked Again in the U.S. to an Outbreak of the Feared ‘CRE’ Superbug(October 2018)
  3. A Duodenoscope Has Been Linked to ‘Probable Transmission’ of a Colistin-Resistant Superbug(December 2017)
  4. Gastroscopes Now Linked to ‘Superbug’ Infections, Too(December 2016)


Article by: Lawrence F Muscarella, PhD. Posted May 30, 2019. Copyright (2019). LFM Healthcare Solutions, LLC. All rights reserved. Dr. Muscarella is the president of LFM Healthcare Solutions, LLC, an independent quality improvement company. Click here for more details about his quality improvement healthcare services

Source: This posting is based on the guidance provided in the more detailed article with the following citation: Muscarella LF. Selection of Low-Temperature Sterilization for the Prevention of Multidrug-Resistant Bacterial Infections During Flexible Endoscopy. Ambu: Columbia, MD. 2019.



E: Larry@LFM-HCS.com. Twitter: @MuskiePhD