Endoscopy Practice and Safety
Editor: Peter B. Cotton
Infection control in endoscopy: Commentary
A. T. R. Axon
This chapter on infection control in endoscopy by Alistair Cowen and Dianne Jones is a comprehensive, thoughtful and well-written
contribution from a group that has had longstanding interest and expertise in this area.
Most endoscopists are not interested
There is an extensive literature about the problems of disinfection of endoscopy equipment, and a plethora of guidelines advising
how to minimize the risk of cross-infection. However, it must be admitted that endoscopists usually try to avoid reading or
thinking about, or being involved with disinfection matters unless they are part of a working group set up to establish regulations,
or they wish to write up an interesting case of cross-infection, or are involved in litigation as a result of the failure
of procedures in their own department. The responsibility for preventing cross-infection has therefore been devolved largely
to the nursing staff. Endoscopists can add to the problem by placing heavy demands on their nursing staff by pressing for
a fast turn-round of equipment in order to complete their lists. This lack of empathy with endoscopic disinfection is understandable
but problematic. As exhortation has not changed attitudes, consideration should be given to other means of ensuring that appropriate
safety standards are maintained.
Is the problem declining?
Dr Cowen's chapter points out that assessments of patient-to-patient transmission based on retrospective analyses are almost
certainly underestimates of the risk. In the 1980s there were a large number of case reports describing single episodes of
cross-infection, and indeed some epidemics. Although many fewer are now reported, this does not necessarily imply that their
number has declined. Whereas the original papers drew attention to what was then a new risk, editors today are unlikely to
accept 'me too' case reports of Pseudomonas septicemia following ERCP, or cases of salmonella transmission.
Newly recognized infections
Interest has focused on the transmission of newer organisms such as hepatitis C. Although the majority of reports have been
attributed to inadequate instrument reprocessing or poor intravenous sedation technique, some cases of infection do appear
to have been transmitted by endoscopy in spite of reasonable precautions having been taken. Furthermore some viruses produce
an initial subclinical infection (which may still lead to a carrier state or chronic disease), or there may be a significant
incubation period in other cases. Under these circumstances post-endoscopy infection will be missed and therefore under-reported.
This is particularly relevant when considering the statement that no case of HIV infection or variant CJD has been shown to
have been transmitted endoscopically. That does not mean that infection has never been transmitted. A number of more recent
reports of H. pylori transmission show that transmission of vegetative organisms still occurs. The observation that, in most of these instances,
the disinfection procedure was improperly performed is no excuse. It merely draws attention to the fact that a number of endoscopy
units do not reprocess their equipment properly according to official guidelines.
Compliance with guidelines
The chapter draws attention to studies that confirm the lack of compliance with cleaning and disinfection protocols, with
more than 50% of units not following the guidelines. It also states that there is evidence of a substantial improvement in
recent years, quoting two papers from the United States. In one of these, questionnaires were mailed to 730 randomly selected
members of the ASGE , and appropriate disinfection methodology was used by 90.7% of respondents. There are three comments that should be made.
Firstly, according to this survey, almost 10% of the units were using inadequate techniques. Secondly the data published was
based on statements made by individuals, and the endoscopy process in the units was not independently inspected by the researchers.
Thirdly the response rate to the questionnaire was a mere 40.3%, which could indicate significant selection bias.
What can be done to remedy this sorry state of affairs?
As was intimated earlier, the responsibility for ensuring adequate disinfection is largely delegated to nursing staff. Nurses
in charge of endoscopy, particularly in smaller units, may be relatively inexperienced, or may not have been given the status
or administrative support required for them to take a hard line with medical staff vis-à-vis the turn-round time of equipment.
Infection control staff
The responsibility for ensuring that endoscopy disinfection is adequate should be entrusted to a senior hospital employee
with a background in hospital cross-infection. Endoscopists generally lack the interest (and even knowledge!) to be suitable
applicants for the job. In the UK one individual (usually someone with knowledge of microbiology) is designated as being responsible
for policing the cross-infection policy of the hospital. This probably pertains in other countries as well. It might be appropriate
for this person to be legally responsible for ensuring that endoscope disinfection is performed properly. If so, a suitable
job description might include the requirement for ensuring that adequate training is given to endoscopists and endoscopy assistants,
that suitable equipment is available, that the day-to-day activities are overseen by a competent member of the nursing staff,
and, most importantly, that regular audit of disinfection is performed. This approach would enable a quality assurance system
to be introduced.
In our unit, each channel of every duodenoscope is swabbed weekly for microbiological culture, as are the endoscope reprocessors.
However, when starting to write this article, I discovered that the gastroscopes and colonoscopes are not put through this
rigorous check because the risks of infection from Pseudomonas in these procedures is small. Swabbing of all equipment at regular intervals would provide a check on the adequacy of the
disinfection process. As most viruses are more easily eliminated by high-level disinfection than vegetative organisms, failure
to grow contaminants would imply by proxy that the disinfection process is working adequately for most organisms.
We recently circulated a questionnaire to members of the British Society of Gastroenterology in order to ascertain whether
this kind of audit was being undertaken in the UK . We found that only 25% of 200 selected endoscopy units were routinely sampling their endoscopes and only 37% their reprocessors.
Over the years that we have been auditing our disinfection procedures, apart from episodes of Pseudomonas contamination which have required attention periodically, we have identified mycobacteria in the hospital water supply resistant
to glutaraldehyde. As a result we have had to change from glutaraldehyde to acidic electrolysed water, which provides high-level
disinfection without the danger of staff toxicity or environmental pollution, and has the added advantage of providing inexpensive
sterile rinsing water. The drawback to this system is that it causes deterioration of the outer surface of the endoscope insertion
tube in certain makes of endoscope.
The role of industry
Manufacturers of endoscopes, reprocessors and disinfectants have important roles to play in improving disinfection technology.
It would be desirable for all endoscope channels to be accessible for brushing. There is, as is often stated, no substitute
for thorough mechanical cleaning. This cannot be undertaken unless the channel can be accessed with a brush. Non-toxic, effective,
inexpensive disinfectants must be developed together with the instrument manufacturers to ensure that our endoscopes and equipment
as well as our staff and patients are safe.
Manual cleaning is key
Every article on endoscope disinfection, including Dr Cowen's, emphasizes repeatedly that the most important step in endoscope
disinfection is thorough manual cleaning. Is it not time to concentrate our efforts to ensure that this takes place?
1 Cheung, RJ, Ortiz, D & DiMarino, AJ Jr. GI endoscopic reprocessing practices in the United States. Gastrointest Endosc 1999; 50: 3628. PubMed
2 Rembacken, B, Butler, A & Axon, A. What is happening in the British endoscopy units? Endoscopy 2000; 32 (Suppl. 1): E65.
Copyright © Blackwell Publishing, 2003