Strong Evidence for Sterilization of Endoscopes Presented at Stakeholder Meeting

Posted September 13, 2017

Evidence indicating that sterilization is a superior method to high-level disinfection (HLD) for the reprocessing of endoscopes was reported during a meeting held on Sept. 11 at AAMI headquarters in Arlington, VA. In addition to not reducing microbial contamination as effectively as sterilization, reprocessing endoscopes using HLD is overly complex and involves far greater risks to patient safety.

More than 40 stakeholders representing healthcare professional organizations, manufacturers, testing labs, independent research groups, academia, patient and clinical end user interests, the Food and Drug Administration (FDA) Center for Devices and Radiological Health, and the Centers for Disease Control and Prevention, among others, attended the meeting in person or by teleconference.

William Rutala, MS, MPH, PhD, director of the statewide program for infection control and epidemiology and research professor of medicine at the University of North Carolina (UNC) at Chapel Hill School of Medicine, presented findings indicating a need to forego HLD in favor of sterilization when reprocessing endoscopes.

For nearly 40 years, Rutala has participated in infection prevention teams and conducted research on disinfection/sterilization at UNC Hospitals and UNC School of Medicine. "During that time, every two to three years, there have been newsworthy endoscopy-related outbreaks that resulted in meeting with various professional organizations, industry, and/or government agencies to discuss the outbreaks," he said. "Each time, we would focus on strict adherence to cleaning and endoscope reprocessing guidelines and/or a design tweak—but the outbreaks continue."

In 1968, Earle H. Spaulding described a classification scheme for reprocessing, depending on how an object will be disinfected based on its intended use. According to the scheme, devices in the "noncritical" FDA device class (i.e., objects that touch intact skin only, such as oximeters) require cleaning followed by low-level disinfection (or nongermicidal detergent), "semicritical" instruments (i.e., objects that touch mucous membranes or skin that is not intact, such as tonometers) require cleaning followed by HLD, and "critical" instruments (i.e., objects that enter normally sterile tissue or the vascular system or through which blood flows, such as surgical instruments) require cleaning followed by sterilization.

Rutala proposed that the Spaulding classification for critical items be modified/clarified from “direct contact with sterile tissue” to “direct or secondary/indirectly contact with sterile tissue.” He further noted that when the Spaulding scheme was designed 50 years ago, semicritical items rarely, if ever, penetrated sterile tissue and healthcare did not have an adequate appreciation for the infection risk associated with endoscope reprocessing, with endoscopes used primarily for diagnostic purposes.

HLD of endoscopes provides "no margin of safety," said Rutala, while sterilization will provide an increased safety margin of approximately 6 log10. That is, while HLD can provide a 6 log10 reduction in microbial contamination, sterilization offers a 12 log10 reduction (or sterility assurance level of 10–6). He further noted that while HLD removes or inactivates 10 to 100 million spores, sterilization kills 1 trillion spores.

Rutala summarized the problems with use of HLD for reprocessing endoscopes as follows: "If the margin of safety is so small that perfection is required, then the design is too complex and the process is too unforgiving to be practical in a real-world setting."

He also reported that more outbreaks are associated with endoscopes than any other reusable medical device, and "inadequate cleaning of flexible endoscopes” was the number one hazard in the ECRI Institute’s Top 10 Health Technology Hazards for 2016. Therefore, Rutala reasoned that if the risk of disease transmission associated with endoscopes is eliminated, the risk associated with all medical and surgical devices will in turn be eliminated.

Cori L. Ofstead, MSPH, president and CEO of Ofstead & Associates Inc., in Saint Paul, MN, presented data from studies conducted during 2008 to 2017. Ofstead's research involves visiting healthcare facilities throughout the country and collecting real-world data on a large variety of endoscopes.

Theoretically, HLD should work, said Ofstead. However, the group's research revealed that barriers to effective reprocessing include damaged scopes; use of defoaming agents and lubricants that cannot be removed from scopes (and that harbor biofilm); relying on automated endoscope reprocessors to clean dirty endoscopes; rinsing with contaminated water (which can result, for example, from poorly maintained and dirty tubing, as well as insufficient water filtration system maintenance); failing to dry endoscopes; storing endoscopes in unventilated storage cabinets; using bare hands and dirty containers to transport endoscopes; neglecting to clean, disinfect, and perform preventive maintenance on reprocessing equipment; and not performing sufficient monitoring of reprocessing effectiveness.

Many healthcare facilities investigated by Ofstead's team placed a high value on efficiency, to the point that patient safety was compromised. This emphasis on efficiency, coupled with human factors barriers (e.g., complex designs and instructions for use make it difficult for staff to adhere to all steps in endoscope reprocessing), means that "HLD is cutting it too close," said Ofstead, in that everything has to be done perfectly every time, or "the whole enterprise comes crashing down."

Other than continued use of damaged endoscopes and the use of defoaming agents and lubricants that can't be removed, sterilization addresses all other barriers listed above, noted Ofstead.

Michelle Alfa, principal investigator at St. Boniface Research Centre in Winnipeg, Canada, presented findings showing that repeated use of endoscopes leads to gradual accumulation of debris, which can lead to microbial survival following disinfection.

As a result, said Alfa, better cleaning methods are needed to provide complete contact (i.e., friction) with inner-channel surfaces to ensure removal of debris after repeated reuse. The current lack of friction methods for cleaning the air/water channel is a major concern, she added.

In addition to supporting the transition to sterilization for all endoscopes, Alfa emphasized the importance of sterile storage for all endoscopes that secondarily contact sterile body sites. Unless these measures are taken, survival of bacteria will occur.

"Reprocessing of endoscopes needs to be treated like an operating room procedure," said Alfa, meaning that the same degree of meticulous attention to detail is needed, each and every time.

The stakeholders in attendance agreed that the move away from HLD to sterilization of endoscopes is a heavily nuanced issue and something that would need to happen gradually. During the AAMI Fall Sterilization Standards Week meeting, October 16–19 in Baltimore, MD, Working Group 84 for Endoscope Reprocessing (AAMI ST/WG 84) will meet to discuss the next steps related to taking these findings into consideration for the revision of ANSI/AAMI ST91, Flexible and semi-rigid endoscope reprocessing in health care facilities.