Microbiological surveillance is an important quality assurance tool in endoscopy and
have been established in many countries for more than 20 years [1]. The aim of microbiological surveillance is to check the quality of endoscope reprocessing,
to confirm the reprocessing quality or to identify possible weak points at an early
stage and to provide information about possible risks. Microbiological surveillance
can also give indications of possible defects in endoscopes and washer-disinfectors,
so that you can react at an early stage.
In outbreak management, microbiological surveillance is a helpful tool to better understand
the situation and find the actual cause that may have led to the transmission of pathogens.
Publications on outbreaks in GI endoscopy usually describe the situation in one institution
and can only be a snapshot.
In reviews the data evaluation from published outbreaks is a challenge because the
reprocessing methods are subject to national differences and have changed over the
years. The comparison of microbiological surveillance programmes is very difficult
because methods of sampling, the time of sampling, the number of channels checked,
the type of sampling solution used, the cultivation methods (filtration vs centrifugation)
and the interpretation of the results show extreme variations [1]
[2]. More homogeneous data are available when the outbreaks are evaluated at national
level [3].
When microbiological surveillance programmes are developed and tested, this is usually
done in one institute with a limited range of endoscopes and over a limited period
of time.
The present work by Pineau is a multi-centre evaluation in France over the impressive
period of 17 years. The evaluation is based on the recommendations of the French guidelines
[4], which were adapted over the course of the study to the new established methods
for duodenoscope sampling [5]. The study of Pineau reflects the situation across France by including all endoscopy
departments in private and public clinics [6]. Due to the national character, endoscopes from different disciplines could be evaluated,
which differed in endoscope types, manufacturers, design and channel geography. Due
to the large number of clinics involved and the wide range of variations of endoscopes
involved, a really complete picture of the reprocessing situation in France was created.
The sampling performance was the responsibility of one institute that operates nationwide
and used uniformly trained personnel with a uniform method protocol. As a result,
there are no institute-related variations here either. Due to the impressive number
of 90311 samples and the uniform sampling in 490 private and public clinics in France,
extensive homogeneous data is available. In this way, trends and critical points can
be derived. What do we learn from the publication?
Improvement of reprocessing quality
Improvement of reprocessing quality
Pineau showed the positive effect of microbiological surveillance on the quality of
endoscopy reprocessing. The rate of detected contaminations has improved continuously
over the past 17 years (19.7 in 2004 to 13.0 % in 2021 at the action level; from 27.8 %
in 2004 to 21.1 % in 2021 – action plus alert level). The contamination rates are
consistent with other national publications [1]
[2]
[3]. It is interesting to see that the overall microbial quality of Gastroscopes, Colonoscopes
and Duodenoscopes has improved in the 17 years of observation while contamination
rates of Bronchoscopes and EUS Scopes has increased. The study could not explain this
effect. But it underlines the necessity to bring the focus to the entire variation
of reprocessed endoscopes. In recent years the focus was projected on duodenoscopes.
It is important to consider that possible errors can be derived from the germs found.
Timing of microbiological surveillance
Timing of microbiological surveillance
Bacteria can be cultivated more easily if sampling is not carried out immediately
after finishing the reprocessing cycle. Therefore, GESA-GENSA [8] and CTINILS [4] recommend microbiological surveillance at the earliest 12 or 6 hours after reprocessing.
This was taken into account by Pineau. Sampling directly after endoscope reprocessing
would have the risk of false negative results.
Staff training
Pineau indicated that specially trained personnel performed the sampling of endoscopes.
This is an important aspect for the practical implementation of microbiological surveillance.
Sampling should be carried out jointly by specially trained endoscopy and hygiene
staff so that the construction of the respective endoscope, in particular the complex
channel configuration, is well known and professional endoscopy handling is guaranteed;
on the other hand the required hygiene expertise for sampling and culturing is needed.
Aseptic techniques during sampling are important. This includes the use of sterile
sampling equipment, the use of PPE with sterile gloves and the disinfection of the
environment prior to sampling in clean work areas. It is advisable to carry out the
sampling with two persons to ensure aseptic sampling and to avoid recontamination
from the environment. The latter would lead to false positive results.
More intensive sampling of critical components
More intensive sampling of critical components
Since the 2000 s, duodenoscopes have been the focus of attention due to reported outbreaks
with multidrug-resistant germs after ERCP in the US and Europe. In a Dutch national
wide study, 22 % of duodenoscopes showed contamination [3]. In the present study, 8 % of duodenoscopes were at the action level and 17.2 %
including the alert level [6]. Under pressure from the FDA, endoscope manufacturers developed removable disposable
distal caps that made cleaning the albarran elevator easier [9]. More intensive methods for sampling at the elevator lever have been established
[4]
[5]. These methods included increased flushing and brushing activities.
While duodenoscope contamination decreased over the years, Pineau showed an increase
in contamination of ultrasound endoscopes (EUS) and other high-risk endoscopes. This
underlines the considerable need for staff training and awareness when dealing with
complex endoscopes. Endoscopy staff need to follow manufacturer´s recommendations
which often is a problem when reprocessing staff is working under time pressure [10]. Single-use components would also be advantageous for these endoscopes. Guidelines
should not only focus on the elevator mechanism at duodenoscopes, but also on sampling
critical components of other endoscopes in general.
Improved sampling methods
Improved sampling methods
In the past, microbiological sampling was described with the pure rinsing of saline
solution (NaCl 0.9 %) [11]. Pineau modified the rinsing solution to better dissolve contaminants. The Tween
80 lecithin-based solution is more efficient than saline solution in detecting contamination
in endoscopes [1]
[12].
Bacteria can react under stress (e. g. disinfectant residues, drying or heat) with
a reduced metabolic state (VBNC: Viable but non-culturable status), which can make
cultivation more difficult. Therefore, guidelines and authors of studies recommend
to add a neutralizer to sampling solutions [1]
[11].
Studies showed that the use of brushes (flush-brush-flush method) and/or an improved
flushing techniques (flush-suction-flush method) can significantly improve the recovery
rate [1]
[3]
[13]. Pineau used the intensified flush-suction-flush method to better loosen residuals
by turbulence effects. Rauwers and Wehrl demonstrated a better recovery rate by using
the flush-brush-flush method [3]
[13]. The higher recovery rates reduce the risk of false-negative results because inadequately
reprocessed endoscopes are more likely to be detected, which improves the safety of
patients and staff [13].
After sampling Pineau used that membrane filtration method before the entire sample
volume was incubated for 5 days in agar plates. A review of Alfa et al also concluded
that the filtration technique improves the culture sensitivity [1].
The knowledge of these improved methods should be considered when national and international
guidelines will be updated.
Interpretation of results
Interpretation of results
According to the French guidelines, Pineau differentiated between different action
and alert levels. There are great variations in national guidelines concerning acceptable
number of germs, action and alter levels [1]
[4]
[5]
[11]. But there is a worldwide consensus that the presence of indicator germs is the
exclusion criterion (“Cutoff”) to continue the use of the sampled endoscope. In case
of contamination with indicator germs, it is the responsibility of the clinical service
provider to take the suspect endoscope out of service until corrective actions have
been taken and satisfactory results have been achieved [13]. In the case of automated reprocessing, the automated endoscope washer−disinfector
and the water used in reprocessing should also be tested at the same time as the endoscopes,
in order to identify the possible cause of infection [13].
It might be helpful to include more detailed guidance in national guidelines how to
interpretate results and to manage the relevant actions [1].
Conclusion
Microbiological surveillance is a helpful and efficient tool of control and evaluate
the quality of endoscope reprocessing. The results can be used to find the source
of infections and to identify weak points and insufficiencies. New methods for sampling
should be taken into account when national and international guidelines will be updated.
