Risk of Flexible Endoscopes, Including Gastroscopes and Echoendoscopes, Transmitting “Superbugs” Infections

by Lawrence F. Muscarella, PhD


“Superbug” infections linked to newer models of duodenoscopes featuring a sealed channel design were first recognized in 2012. This article provides a review of the published medical literature and of the FDA’s medical-device database to evaluate the potential for other types of flexible endoscopes to transmit multidrug-resistant bacteria, including carbapenem-resistant Enterobacteriaceae, or CRE. Several cases document the contamination of bronchoscopes, cystoscopes, curvilinear-array echoendoscopes, flexible laryngoscopes, gastroscopes and ureteroscopes with concerning bacteria, and in some cases these devices were linked to superbug infections or outbreaks. Public notices focusing on the potential for these other types of flexible endoscopes, too, to transmit superbugs are few, however, suggesting that these devices may pose an under-recognized risk of multidrug-resistant bacterial infections. Recommendations for preventing these devices from infecting patients with potentially untreatable bacteria are provided, including that users consider applying at least one enhanced practice, previously recommended by the FDA to mitigate the risk of duodenoscopes transmitting superbugs, to these other types of flexible endoscopes, as deemed appropriate, feasible and warranted, particularly to curvilinear-array echoendoscopes, which like duodenoscopes feature a forceps elevator mechanism. Efforts to increase public awareness about the potential for these devices to infect patients with superbugs is recommended.

Introduction and Background

Almost six years ago, a hospital in the Netherlands linked an outbreak of VIM-2-producing Pseudomonas aeruginosa to gastrointestinal (GI) endoscopy.[1] Twenty-two (22) patients tested positive for this superbug after undergoing endoscopic retrograde cholangiopancreatography, or ERCP, performed in 2012 using a duodenoscope model that features a sealed channel design. The investigation reportedly was the first to link this model to an infection cluster of a carbapenem-resistant superbug.[1] While one of this duodenoscope model’s channels, known as the elevator-wire channel, is intended to be closed to prevent contamination, this channel in some older duodenoscope models is open requiring cleaning and disinfection – or, reprocessing – after each procedure. No significant gaps between the hospital’s reprocessing practices and the duodenoscope manufacturer’s instructions were identified; however, investigators recovered VIM-2-producing P. aeruginosa clonally related to the outbreak’s strain under the duodenoscope’s forceps elevator mechanism.[1] Removal of this duodenoscope model from clinical use terminated this hospital’s outbreak.

The next year, a hospital near Chicago (IL) similarly linked ERCP to an outbreak of NDM-1- producing E. coli, which is a type of carbapenem-resistant Enterobacteriaceae, or CRE.[2-4] Like the outbreak in the Netherlands,[1] bacteria closely related to the outbreak’s superbug were recovered from a reprocessed duodenoscope.[2,3] No additional infections of CRE were identified once the hospital began sterilizing duodenoscopes using ethylene oxide (EO) gas.[2] The investigation of this CRE outbreak in 2013 was notable for a number of reasons. First, it confirmed that carbapenem-resistant superbugs could be transmitted during GI endoscopy, specifically ERCP[1-10]. Second, for the first time in the U.S., an outbreak of CRE had been publicly linked to a duodenoscope model1 with an elevator-wire channel designed to be sealed or closed.[2,3] Third, the duodenoscope reportedly remained contaminated with CRE despite the hospital apparently having correctly reprocessed the device in accordance with the manufacturer’s instructions,[2,6] a finding other studies have similarly reported.[1,6,7] As the FDA has previously warned, duodenoscopes may transmit multidrug-resistant bacteria “despite confirmation that the users were following proper manufacturer cleaning and disinfection or sterilization instructions.”[8] Publicizing this risk, the FDA advised in February 2015 that duodenoscopes may impede effective reprocessing.[7] The FDA further advised that meticulous cleaning of duodenoscopes “should reduce the risk of transmitting infection, but may not entirely eliminate it.”[7]

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Risk of “Superbug” Infections during Flexible Endoscopy Copyright © 2018. All rights reserved. The Ruhof Corp.

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