January 24, 2024 (by: Lawrence F Muscarella, PhD) – Just weeks ago — and now publicized for the first time — 17 patients at a U.S. medical facility were exposed to a single colonoscope found to be contaminated with potentially dangerous Salmonella bacteria, several regulatory reports submitted to FDA in December reveal.
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Highlights
- Reports suggest the risk of patient exposure and cross-infections from a contaminated colonoscope may be significantly more common occurrences than reported.
- Just weeks ago, 17 patients at a U.S. medical facility were exposed to a single colonoscope found to be contaminated with potentially dangerous Salmonella bacteria, according to more than 30 apparently related manufacturer reports submitted to the FDA in December (2023).
- Previous cases linking the use of colonoscopes, as well as gastroscopes, to Salmonella infections are discussed.
- Salmonella exposure during an endoscopic procedure can result in cross-infection, including gastroenteritis, bacteremia, and septicemia. Strains of the bacteria resistant to “last-resort” antibiotics may be the feared carbapenem-resistant Enterobacterales, also known as the CRE superbug.
- A related, unpublished analysis by this article’s author identified approximately 650 adverse event reports submitted to FDA in December alone, including these several Salmonella reports, describing ineffective cleaning of a colonoscope.
- Based on that analysis, a projected estimation suggests the possibility that thousands of adverse events reports could be submitted to FDA in 2024 describing the ineffective reprocessing of a gastrointestinal endoscope and associated patient exposures.
- By any reasonable measure, this estimated number of FDA adverse event reports is significant and argues for prompt adoption of corrective actions validated to improve colonoscope safety.
- Publication of a federal safety alert to raise awareness, improve colonoscope safety, and provide updated guidance to reduce the risk of reprocessed colonoscopes remaining contaminated and infecting patients with potentially life-threatening bacteria is recommended.
- Additional recommendations to reduce the risk of a GI endoscope exposing patients to infectious organisms including Salmonella and CRE are also provided.
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January 24, 2024 (by: Lawrence F Muscarella, PhD) – Just weeks ago, 17 patients at a U.S. medical facility were exposed to a single colonoscope found to be contaminated with potentially dangerous Salmonella bacteria, according to more than 30 apparently related adverse event reports submitted to the FDA in December (2023).
Prior to these 17 patients, this same colonoscope reportedly had been used to perform a diagnostic procedure on a patient for suspected colitis. Following this procedure and also a subsequent surgery, this earlier patient, described in the reports as the “initial” patient, was diagnosed with Salmonella.
Salmonellosis is an infection that can be transmitted from patient-to-patient by the fecal-oral route. The organism can be found in human intestines, raising concerns about the potential for a gastrointestinal endoscope to cross-infect patients with Salmonella and related bacteria.
After learning of this initial patient’s diagnosis, the medical facility’s infection control department tested the suspect colonoscope and found it contaminated with Salmonella, but only after the device had already been used on the 17 exposed patients — and despite this contaminated colonoscope being reprocessed with high-level disinfection 17 times, once after each of the patients, in accordance with the manufacturer’s instructions for use, the FDA reports state.
I reviewed every adverse event report submitted to FDA in December (2023) involving ineffective reprocessing of a colonoscope and identified approximately 650 reports just in this one month alone, raising questions about whether patient exposure to a contaminated colonoscope may be significantly more common than currently recognized. — Lawrence F Muscarella, PhD
While cases describing patient exposures to a colonoscope harboring Salmonella are notable in part because they are infrequently documented, reports linking the use of gastrointestinal equipment — namely, colonoscopes and gastroscopes — to Salmonella infections have been published, though the more common modes of salmonellosis transmission among humans are from contaminated food and water.
Strains of Salmonella displaying resistance to “last-resort” antibiotics may be the feared carbapenem-resistant Enterobacterales, also known as the CRE, with associated mortality rates of as high as 50% or more.
While colonoscopes are used to examine the inside of the colon, gastroscopes are used to examine the stomach and other portions of the upper GI tract.
For its part, the colonoscope’s manufacturer states in these December FDA reports describing this Salmonella incident that “we may conclude the endoscope itself is not the primary problem of this contamination, but that it most likely concerns failure modes in the reprocessing.”
Infection Case Reviews, Expert Guidance: LFM-Healthcare Solutions, LLC provides medical expertise for legal representatives, device manufacturers, and medical facilities specializing in healthcare-associated infections linked to contaminated reusable medical equipment.
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All affected patients notified? The FDA’s December reports do not clearly state whether each of the 17 affected patients were informed of their potential exposure to and infection from the Salmonella. The FDA reports state, however, that “the awareness date for the 17 additional patient cases” was December 15, 2023, and that only the original patient was confirmed to have the Salmonella.
Salmonella exposure can result in infections such as gastroenteritis, bacteremia, and septicemia. While millions of people are infected with Salmonella annually in the U.S. due to ingesting contaminated food or water, only a few hundred reportedly die.
Several factors could have contributed to these 17 patients being potentially exposed to the Salmonella bacteria, including undetected damage to the colonoscope’s working channel, the formation of an inaccessible Salmonella biofilm inside the colonoscope, and/or the failure to maintain and service the colonoscope according to manufacturer instructions. – Lawrence F Muscarella, PhD
Evaluation of the 17 affected patients for possible infection might include testing stool samples for Salmonella.
Further, these December reports state that “no species identification was performed.” Confirmation that an implicated endoscope was contaminated with the same (or a genetically related) organism as an infected patient, however, can be important to understanding the chain of transmission.
Forensic Case Reviews, Infection Investigations: LFM-Healthcare Solutions, LLC provides medical expertise for legal representatives, device manufacturers, and medical facilities specializing in healthcare-associated infections linked to contaminated reusable medical equipment.
Possible causes: The reviewed FDA reports do not identify the specific error or missteps that may have caused or contributed to these patients being exposed to the single colonoscope harboring Salmonella.
Possible factors that may have contributed to the apparent ineffective reprocessing of this colonoscope include:
- faulty cleaning and/or high-level disinfection of one of the colonoscope’s internal channels or the air/water nozzle (notwithstanding the FDA reports’ indication that the colonoscope was properly reprocessed per the manufacturer’s instructions)
- damage to the colonoscope (e.g., a tear inside working channel, or a device defect)
- an inaccessible, persistent biofilm forming inside the colonoscope
- the high-level disinfectant (if reusable) was below its minimum effective concentration
- failure to maintain, service and repair the colonoscope according to the manufacturer’s recommendations
- an unqualified third party repairing the colonoscope using uncertified parts
- mishandling the colonoscope, or using it in a contaminated environment
- possibly, use of contaminated water to rinse the colonoscope after high-level disinfection.
Other infection posts: Some of Dr. Muscarella’s other postings that focus on the risk of colonoscopes transmitting infections include:
- “A Colonoscope is Linked to Two Infections of the Nightmarish ‘CRE’ Superbug” (January 2019)
- “At Least 40% of Disinfected Endoscopes, Possibly Colonoscopes, Remained Contaminated, Emails Reveal” (July 2016)
- Contamination of Flexible Endoscopes and Associated Infections” (January 2022)
Salmonella infections linked to colonoscopy: While infrequently reported, cases linking colonoscopy to Salmonella infections have been published.
Dwyer et al. (1987), for example, linked an outbreak of Salmonella newport to colonoscopy. The endoscopic equipment most likely became contaminated when an initial patient diagnosed with acute Salmonella newport gastroenteritis underwent colonoscopy, the report concluded.
The report further explained that: “Inadequate disinfection of the equipment allowed the organism to survive and possibly to cross-contaminate other colonoscopes, and the organism was then transmitted to other patients by use of the contaminated colonoscopes or the contaminated biopsy forceps.”
In addition to Salmonella newport, other relevant species of this gram-negative organism include Salmonella enteritidis and Salmonella zanzibar.
More recently, Reddick et al. (2017) reported three patients with identical isolates of Salmonella enteritidis following colonoscopy performed on each using the same colonoscope within a period of eight days in the same hospital.
These investigators concluded that this outbreak supports the suggestions of others that “transmission of salmonella can occur during colonoscopy with contamination occurring directly to the lower gastrointestinal tract.”
FDA reports submitted the same year (2017) describe the fecal samples of five (5) colonoscopy patients testing positive for Salmonella zanzibar. Each of these patients was exposed to a single colonoscope, although the device tested negative for the bacteria.
More recently, FDA received a report in 2021 describing a patient diagnosed with Salmonella infection two days after undergoing colonoscopy. Although stains and a tear mark were visually identified inside the endoscope’s biopsy channel suggesting the potential for inadequate cleaning and damage, the colonoscope tested negative for Salmonella.
Related peer-reviewed articles by Dr. Muscarella: The author of this article discussing these 17 cases (Dr. Muscarella) has previously published in the peer-reviewed literature on the risk of contaminated colonoscopes transmitting bacteria:
- “The Study of a Contaminated Colonoscope” (Muscarella LF, 2010)
- “Risk of transmission of carbapenem-resistant Enterobacteriaceae and related ‘superbugs’ during gastrointestinal endoscopy” (Muscarella LF, 2014)
- “Current issues in endoscope reprocessing and infection control during gastrointestinal endoscopy” (Nelson DB, Muscarella LF, 2006) (The article specifically addresses the risk of a colonoscope transmitting Salmonella)
An underestimated infection risk? Accurate assessments of the risk of infection following colonoscopy, including from an GI endoscope contaminated with Salmonella, are difficult to calculate in part because the infection data necessary for such an accounting are reportedly incomplete due to underreporting, among other factors.
Nonetheless, estimates have been published.
In previous years, the risk of a GI endoscope transmitting disease to a patient was estimated to be much less frequent, or 1 in 1.8 million. Similarly, Deb et al. (2022) and other researchers reported the incidence of infection following lower gastrointestinal endoscopic procedures (i.e., colonoscopy) to be low (e.g., less than 0.1%).
Other investigators, however, including Wang et al. (2018) reported that infections following colonoscopy (performed in ambulatory surgery centers) “are more common than previously thought” (e.g., 1-2 infections per 1,000 procedures). In another study, Lin et al. (2017) reported that colonoscopy patients had almost a 10-fold risk of infection compared with the control group.
These studies and others suggest, therefore, that today’s true infection risk associated with colonoscopy may be significantly higher than generally recognized.
Further hindering more accurate estimates of the infection risk, post-endoscopy surveillance of patients for disease transmissions is not routinely performed in the U.S., and when practiced, these monitoring systems may not be sufficiently sensitive or adequately designed to detect and count all bacterial (and viral) transmissions.
(Note: As many as 15 million colonoscopies are performed in the U.S. each year. While a 2022 landmark study suggests the benefits of colonoscopies for cancer screening may be “overestimated,” colonoscopy for cancer screening can be an important lifesaving procedure.)
Need guidance investigating the cause (and prevention) of a healthcare-associated infection or outbreak? LFM-Healthcare Solutions, LLC provides medical expertise for legal representatives, device manufacturers, and medical facilities specializing in healthcare-associated infections linked to contaminated reusable medical equipment.
An FDA database analysis: This article’s author analyzed and reviewed adverse event reports, submitted to FDA in December (2023), describing ineffective reprocessing of a colonoscope, including this Salmonella case.
This analysis identified approximately 650 reports (in this one month alone) describing ineffective reprocessing (e.g., faulty cleaning, a clogged channel) of a colonoscope. Almost 100 of these reports identify “microbial contamination” of the colonoscope (including with Salmonella) as the reportable adverse event.
In general agreement with Wang et al. (2018), these findings suggest that the number of patient exposures to a contaminated colonoscope, with and without documented infection, may occur considerably more often than previously recognized.
I recommend publication of federal safety alert focusing on the risk of reprocessed colonoscopes remaining contaminated and potentially exposing patients to infectious bacteria. Such a measure would likely enhance compliance with well-established safety measures and contribute significantly to reducing the contamination and infection risk. – Lawrence F. Muscarella, Ph.D.
Based on the approximately 650 reports FDA received in December alone, a projected estimation suggests the possibility that thousands of adverse event reports could be submitted to FDA in 2024 describing the ineffective reprocessing of a GI endoscope, unless enhanced mitigations are adopted to reduce the risk.
By any reasonable measure, this estimated number of FDA reports is significant and argues for prompt adoption of corrective actions validated to improve colonoscope safety.
And this estimate of FDA reports in the next year could be even higher. Kim et al. (2019) reported that “the actual incidence of colonoscopy-related adverse events may be higher than reported.”
FDA safety alert: The author of this article has previously suggested that FDA consider publicizing the potential for reprocessed colonoscopes, and gastroscopes too, to remain contaminated and potentially expose patients to bacteria including multidrug-resistant organisms.
The FDA’s alert could be modeled after the FDA’s recently published safety alerts and communications focusing on reports of reprocessed bronchoscopes, duodenoscopes, and urological endoscopes remaining persistently contaminated despite their being cleaned and high-level disinfected (or sterilized) in accordance with manufacturer recommendations.
Recommendations: The issuance of an FDA alert to raise awareness, improve colonoscope safety, and provide updated guidance to reduce the risk of colonoscopes infecting patients with potentially life-threatening bacteria is again recommended.
Other recommendations designed to reduce the risk of patient exposure to a colonoscope contaminated with Salmonella, CRE and other infectious organisms include:
- reprocessing the colonoscope in accordance with manufacturer instructions
- properly maintaining, serving and repairing the colonoscope
- leak testing and visually inspecting the colonoscope to detect defects or other types of damage
- properly handling and storing the colonoscope
- having in place a comprehensive quality assurance program that ensures the colonoscope’s reliable and effective cleaning and high-level disinfection
- if the technology is available, consider using a sterilized colonoscope when feasible
- post-endoscopy surveillance of patients for disease transmissions.
Summary: Reports suggest the risk of cross-infections due to a contaminated colonoscope may be significantly under-reported. Additional measures, including the issuance of an FDA alert to raise awareness, improve colonoscope safety, and provide updated guidance to reduce the risk of reprocessed colonoscopes remaining contaminated and infecting patients with potentially life-threatening bacteria, are recommended.
Article limitations: Adverse event reports submitted to FDA have two notable limitations.
First, a report linking or associating a colonoscope or other type of flexible endoscope with an infection does not confirm the endoscope transmitted or otherwise caused the infection, as one or more other factors could be, in part or solely, responsible. Additional data would be required to conclude more definitively that the endoscope caused the infection.
Second, adverse event reports listed in the FDA’s “MAUDE” database, according to FDA, have not been independently reviewed and could potentially be “inaccurate, untimely, unverified, or biased,” Nor, according to FDA, are adverse-event reports “by themselves, definitive evidence of a faulty or defective medical device, and cannot be used to establish or compare rates of event occurrence.”
Nevertheless, FDA routinely uses the MAUDE database to monitor the safety of medical devices and specifically flexible endoscopes (e.g., bronchoscopes, duodenoscopes and urological endoscopes), and to develop important recommendations to reduce the risk of patient harms.
Article by: Lawrence F Muscarella, PhD. LFM Healthcare Solutions, LLC. Dr. Muscarella is the president and founder of LFM Healthcare Solutions, LLC, an independent quality improvement company. Click here for a list of his quality improvement healthcare services. E: Larry@LFM-HCS.com. [LFM-ver-1.5]
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Sponsorship: The research and writing of this article was sponsored, in part, by AMBU, which received FDA clearance in 2023 for a sterile, single-use, flexible colonoscope.
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Forensic Case Reviews, Infection Investigations: LFM-Healthcare Solutions, LLC provides medical expertise for healthcare facilities, device manufacturers and the public, specializing in healthcare-associated infections linked to contaminated reusable medical equipment.
Dr. Muscarella’s expertise, experience:
Dr. Muscarella is an expert in the causes and preventions of hospital infections linked to endoscopic and other types of medical procedures. He also specializes in forensic case reviews, medical errors, medical device designs, risk assessments and gap analyses. His “bio” is available here.
Dr. Muscarella is an independent safety expert with almost 30 years of professional experience in the relevant fields of medical device design, infection prevention, aseptic technique, risk management, disinfection and sterilization, and endoscope reprocessing.
He has authored more than 200 articles on these topics, including on the causes and prevention of endoscope-related bacterial outbreaks. Several of his peer-reviewed articles have been published in Chest, The American Journal of Infection Control, Gastrointestinal Endoscopy, Infection Control and Hospital Epidemiology, and The Journal of Hospital Infection.
Dr. Muscarella’s research, findings and perspectives on these topics have been discussed by more than two dozen news media outlets, including CNN, NBC’s The Today Show, NBC Nightly News, ABC World News Tonight, Al Jazeera America, and
the CBS Evening News.
Additionally, his guidance and advice have been discussed on the front pages of The Wall Street Journal, The Los Angeles Times, The Seattle Times, The San Juan Weekly, The Seattle Times, and The Denver Post, among other printed newspapers.
More about Dr. Muscarella “bio” may be read here. Copies of his curriculum vitae (c.v.) are available upon request.