Clean and clear? – countering the threat of infection9 May 2014
Flexible endoscopes are associated with more documented cases of healthcare-associated infections (HAIs) than any other type of reusable medical device. Katherine Templar Lewis asks Dr Alex Kallen, medical epidemiologist and outbreak response coordinator for the Centers for Disease Control and Prevention (CDC), how endoscopy units should deal with the threat of an infection that can persist even beyond reprocessing procedures.
In January 2014, the Advocate Lutheran General Hospital, situated just outside Chicago, reported the largest outbreak of carbapenem-resistant Enterobacteriaceae (CRE) the US had ever seen. The lethal superbug was linked to gastrointestinal endoscopic procedures of the pancreas or bile duct conducted on patients between January and September 2013.
The subsequent investigation, led by Dr Alex Kallen on behalf of the Centers for Disease Control and Prevention (CDC), discovered 44 suspected cases of CRE, with 38 of them confirmed. Until then, there had only been 96 reported cases in total across the whole of the US since the identification of the CRE bacteria
While the statistics seem alarming, it is important to keep in mind the difference between exposure and infection. The results of the investigation following the outbreak showed that, while most of the 243 patients screened at the hospital had been exposed to the bacteria in question, the majority of the patients screened were "colonised" rather than infected. In other words, the bacteria were present in the digestive tract, but not actually causing any disease.
However, authorities were right to treat the outbreak seriously. While the bacteria are part of the E coli family, many forms of which colonise the digestive tract without harm, the outbreak involved the CRE NDM-1 strain of the bacteria. CRE is resistant to carbapenem, the "last resort" antibiotic. It is known to most commonly cause an initial urinary tract infection, and from there can spread into the bloodstream.
Run the risk assessment
Kallen outlines why it is that CRE poses such a particular threat to endoscopy units, and why infection prevention is such a challenging task in these units, where there are multiple points that infection control can be accidently breached. He explains how this can occur not only when reprocessing the equipment but also in the more general environment of the unit itself.
"Properly cleaning and disinfecting endoscopes requires facilities to adhere to detailed manufacturer's instructions every time an endoscope is reprocessed to prevent transmission of potential pathogens," says Kallen. "These devices are complex. Add to that issues like staff turnover meaning a need to train new staff, keeping workers updated as the designs and recommendations change and the potential need for rapid reprocessing in a busy clinic, and one can see how ensuring adequate endoscope reprocessing can be difficult."
There is indeed an association between colonisation or infection by CRE and patients who have undergone endoscopic retrograde cholangiopancreatography (ERCP) procedures. The CDC's 'Morbidity and Mortality Weekly Report' from 3 January reported findings of an investigation showing this very link. Previous studies have also shown that, even after proper cleaning and disinfection, bacteria cultures have been found within the devices.
For this reason, the focus of current infection control is on the complex endoscopes and their reprocessing. Gastrointestinal endoscopes, especially the flexible model used in ERCP procedures, are seen as high risk. This model has been linked to healthcare-associated infections at a higher rate than other medical instruments in use. This type of endoscope is commonly used to diagnose and treat diseases in the bile duct and pancreas, and has, by necessity, a complex internal design.
"Duodenoscopes, like the one involved in this outbreak, have a highly complex design. The flexible endoscope has a series of internal channels and valves that needs detailed reprocessing," explains Kallen. "An increased internal surface area naturally makes it more prone to bacterial colonisation.
"Unfortunately, the internal structure is inherent to its accuracy as a device, as well as being important to minimise any discomfort the patient may feel during endoscopic procedures."
The conflict between meeting the needs of accurate diagnosis and the requirements of reprocessing is one Kallen is acutely aware of. While there have been new recommendations made by the CDC for endoscopy units, concerning the reprocessing of the equipment, he is keen to stress that it is not due to any problem in the actual devices.
"We are currently discussing the further evaluation of the duodenoscopes used in this cluster in order to determine if there might be a greater cleaning challenge with these endoscopes. At this point, there is no evidence that there was a "flaw" in the design of the duodenoscope involved in the Illinois outbreak.
"However," he adds, "we continue to work to determine if there might be issues posed by the design that might result in an increased likelihood that they would not be properly cleaned or disinfected. If there are issues like this, then they would need to be addressed, potentially by modifying cleaning protocols or possibly by other means."
It is important to remember that the investigation by the CDC and the Illinois Department of Public Health did not find any evidence of a flaw in the protocol carried out for the disinfection of devices or the measures routinely undertaken to help prevention bacterial infection in the General Advocate Lutheran hospital.
The environment as a whole
Regardless, the hospital did subsequently adopt an even higher level of endoscope reprocessing, beyond even the guidelines set out by the manufacturer; it now employs gas sterilisation of the devices with ethylene oxide. This raises the question, should there be a change in the procedural guidelines set out for reprocessing?
Asked whether endoscopy units should now go above the manufacturer's current sterilisation recommendations, Kallen argues that, while it is still a method approved by the manufacturers, it may not be the best solution in the long term.
"Gas sterilisation was one of the methods approved by the manufacturer for this duodenoscope," he points out. "However, there are a number of potential issues with this method, including the potential toxicity to staff and patients posed by things like ethylene oxide, the considerable delays there can be in endoscope reprocessing with this process and its lack of availability in many outpatient settings.
"All these will likely limit the generalisability of this process. CDC is not currently recommending a broad change to sterilisation," he says.
He is also keen to stress the need to consider the whole environment, not just the medical devices themselves, when tackling infection control.
"The role of duodenoscopes in the spread of CRE is likely very small. CRE is more often spread through person-to-person transmission in healthcare settings or through exposure to contaminated environments. This is being addressed through a large number of programmes sponsored by CDC, state and local health departments, and by healthcare facilities," he says. "However, it's critical that we have confidence that duodenoscopes can be expected to be adequately reprocessed by users - not just for CRE but also for any bacteria or virus. For now, we have some evidence, such as the recent outbreak in Illinois, which makes us concerned there might be, at least at times, issues with duodenoscope reprocessing," he continues.
"We are still trying to evaluate the extent of the issue and whether it is a problem beyond this single instance, as well as what can be done about it. We should not be putting patients at risk unnecessarily," he emphasises.
Putting the patient and their safety first using a whole-environment approach is of paramount importance to the Society of Gastroenterology Nurses and Associates (SGNA), which is dedicated to the safe and effective practice of gastroenterology and endoscopy nursing.
The SGNA also reiterates the need for ongoing education and training, highlighting in a recent paper, published in Infection Control Today, the rapidly developing and changing technology of product design.
The SGNA is a leader in its provision of resources and support to healthcare professionals, and, in June 2013, it launched its SCNA Infection Prevention Champions programme, promoting the selection of a "unit-based champion to carry out the vision and mission of the programme by educating self and staff on infection prevention topics, maintaining high quality control within the endoscopy arena and addressing performance improvement needs". It aims to protect not just the patient but also the healthcare provider.
Kallen states the vital importance of programmes of this kind. He also impresses the importance of the units taking responsibility themselves through constant awareness, internal evaluation and education on top of standard training.
"Right now, CDC continues to evaluate the scope of this issue and develop potential solutions, but this is a broader problem," says Kallen. "It is obviously important for CDC and our partners to get to the bottom of the issues that surrounded the Chicago outbreak to make sure they can be corrected.
"However, at CDC, it is much more common for us to be consulted by health departments or healthcare facilities about a known breach in protocol than instances where no breaches are identified," he points out. "These have resulted in large patient notifications and testing.
"So, I think it is important to focus on what the people reprocessing endoscopes at your facility are doing - are they adhering to the established protocols? Are they being evaluated to make sure that is the case? We do currently recommend that facilities using duodenoscopes adhere exactly to the manufacturer's recommendations for reprocessing, but we also recommend that facilities regularly review their practices to ensure their reprocessing is adherent to those recommendations."
The CRE outbreak in Illinois was a reminder of the inherent challenges to infection control faced by endoscopy units. But Kallen is right to emphasise that, rather than focusing on where there may have been flaws in procedure - when none have in fact been found - it should be instead used by units to look forward.
The outbreak should be used to help facilities develop a heightened responsibility; to remind them of the need not just for device reprocessing care, but also for a whole-environment approach to infection control. It should be used to help ensure constant education, evaluation and awareness in endoscopy units, protecting the patient as well as the healthcare worker.