Introduction
Endoscopic retrograde cholangiopancreatography (ERCP) is well established as a technique
for minimal access endotherapy of biliary and pancreatic diseases. In contrast to
other gastrointestinal endoscopic procedures, ERCP is somewhat vulnerable to transmission
of infections [1]. The side-view endoscope is more difficult to clean and disinfect because of its
side-view orientation, small lumen, multiple channels and the length of insertion
tube [2]
[3]. Flexible gastrointestinal endoscopes show a high rate of microorganisms after use
(from 105 colony-forming units [CFU]/ml to 1010 CFU/ml) [4]
[5]
[6]
[7]. This is especially found when time-consuming therapeutic processes are performed
in the potentially infected biliary and pancreatic tract [8]. Endoscopes are reusable instruments, employed in different patients in a single
day, and appropriate reprocessing of endoscopes and accessories is mandatory prior
to each individual procedure [3]
[9].
The incidence of transmission of infections through flexible endoscopes is very low
and has been found to be 1 in 1.8 million procedures [10]. However, endoscopes have been associated with outbreaks of nosocomial infections
[11]. Since most of the studies were based on culture identification methods, the true
bioburden may have been underestimated because of the likely presence uncultivable
microorganisms and because of biofilm formation. The infection rate may have also
been underestimated because of factors such as incomplete surveillance; underreporting,
and asymptomatic infections [12]
[13]. Hence although the risk of endoscopy-related infection is documented to be very
low, continued efforts are needed to ensure that quality is maintained during endoscope
reprocessing to reduce the incidence of endoscopy-related infections.
A number of studies have highlighted that pathogen transmission related to endoscopy
is due to failure to follow established cleaning and disinfection/sterilization guidelines
or due to the use of defective equipment [12]
[14]
[15]. In addition, improper intravenous administration of anesthetics during gastrointestinal
endoscopy has been found to be another common mode of transmission of pathogens [9]. Although the Centers for Disease Control and Prevention (CDC) have not recommended
routine microbiological surveillance of gastrointestinal endoscopes [16], monitoring of the outcome quality of endoscope reprocessing methods is recommended
by the European Societies of Gastrointestinal Endoscopy (ESGE) and of Gastroenterology
Endoscopy Nurses and Associates (ESGENA) [17].
The purpose of this study was to evaluate the outcome quality of the manual reprocessing
procedure for removal and inactivation of the bioburden from the side-view endoscopes
in a tertiary referral endotherapy unit in Sri Lanka.
Materials and methods
The study was carried out from September 2012 to February 2013 at the endotherapy
unit of the Colombo South Teaching Hospital and the Department of Microbiology of
the University of Sri Jayewardenepura, Sri Lanka.
A total of 102 samples were collected from two different side-view endoscopes (Olympus
TJF Q 180V, Olympus TJF 160 R) that had been used for both diagnostic and therapeutic
purposes, regardless of the underlying disease of the patient.
Sampling for microbiological cultures
The tip and the working channel of the side-view endoscopes were monitored as these
two sites have been shown to have a high bioburden after ERCP [18]. The sampling method, using normal saline and swabs, followed the ESGE – ESGENA guideline for quality assurance in reprocessing: Microbiological surveillance testing in endoscopy [17]. Swabbing is the ideal sampling method for the tip; this is supported by other publications.
Three types of sample were collected from each endoscope. The first sample was taken
(in duplicate) from the tip (including the elevator forceps) of the insertion tube,
using a sterile swab soaked with sterile normal saline immediately after withdrawal
of the endoscope following ERCP. The second swab samples were taken (in duplicate)
after the protocol-based manual reprocessing of the side-view endoscope had been completely
performed. The third sample was obtained after manual reprocessing by collecting 10 ml
of sterile normal saline through the working channel. Sterile saline was injected
into the working channel via biopsy valve using a sterile syringe, and subsequently
collected at the distal tip of the side-view endoscope. Aseptic techniques were applied
during the collection.
The specimens were transported to the bacteriology laboratory at the Department of
Microbiology, Faculty of Medical Sciences, University of Sri Jayewardenepura within
2 hours of collection and were subsequently processed.
Culturing of samples
One of the two swabs taken before and after the procedures was directly inoculated
onto blood agar and MacConkey agar plates. The remaining duplicate swabs taken before
and after the procedure were enriched in brain heart infusion (BHI) broth. The plates
and the broth were incubated for 18 hours at 37 °C. The BHI broths were then inoculated
on blood agar and MacConkey agar plates irrespective of the turbidity. The normal
saline samples were centrifuged at 1500 g for 10 minutes. One drop (0.001 ml) was taken from the sediment, inoculated on solid
media as above, and incubated to obtain isolated colonies [11]. If no growth was seen, plates were incubated for another 24 hours.
Culture results were reported as positive or negative for all the swab samples regardless
of the number of colonies. In acccordance with the ESGE – ESGENA guideline [17], microbial growth with > 20 CFU/channel was considered to be significant growth
for the normal saline samples taken from the side-view endoscopes after reprocessing.
Isolated microorganisms were identified according to standard determination schemes.
Manual eprocessing of side-view endoscopes
In the endotherapy unit at Colombo South Teaching Hospital reprocessing of the side-view
endoscopes is done in accordance with the manufacturer’s instructions. Manual reprocessing
is performed by trained nurses with more than 1 year’s experience in this procedure.
As soon as the ERCP procedure is over, the outer surface of the insertion tube is
wiped using a piece of gauze soaked with a detergent. The working channel is then
flushed by immersing the tip of the scope in the detergent solution and suctioning
the detergent solution through the channnel.
The side-view endoscope is then moved to reprocessing basin (Manual Disinfector TD
20, Olympus) where manual cleaning is performed by washing all debris from the exterior.
All removable parts are separately cleaned. Then, using an all-channel irrigator,
the channels of the scope are flushed with water. The side-view endoscope and the
accessories used are then rinsed in 0.35 % peracetic acid for 10 minutes in a closed
system [16]. The scope is then submerged in filtered water to flush all channels with filtered
water. Finally, the ready-to-use scope is dried using a sterile piece of gauze. The
total time required to carry out manual reprocessing of the side-view endoscope is
about 18 minutes. At the end of the endoscopy clinic, in addition to the manual reprocessing
described above, 70 % isopropyl alcohol is flushed though the internal channels and
allowed to air-dry.
Results
The side-view endoscopes were sampled on 102 occasions, 67 from the Olympus TJF Q
180V and 35 from the Olympus TJF 160 R.
The results of the microbial cultures from the 6-month period are summarized in [Table 1]. After completion of reprocessing, the culture-positive rate for the tips of the
two side-view endoscopes was 20 % (21/102) and that for the working channels was 9 %
(10/102). Out of the 21 culture-positive samples taken from the tip of the reprocessed
side-view endoscopes 71 % (15/21) were from the 1-year-old side-view endoscope (Olympus
TJF Q 180V) while 29 % (6/21) were from the 5-year-old side-view endoscope (Olympus
TJF 160 R). Out of the 10 positive liquid samples, 6 were from the Olympus TJF Q 180V
and 4 from the Olympus TJF 160 R so the culture-positive rates in working channels
were 6/67 (9 %) and 4/35 (11 %) for liquid samples taken from the 1-year-old and 5-year-old
scopes, respectively.
Table 1
Sampling and culture results for the tip (before and after reprocessing) and the working
channel (after reprocessing) of the side-view endoscopes.
|
Type of endoscope
|
Sampling from each endoscope, n
|
Tip contaminated before reprocessing, n
|
Tips contaminated after reprocessing, n
|
Working channel contaminated after reprocessing
|
|
Olympus TJF Q 180V)
|
67
|
61/67
|
15/67
|
6/67
|
|
Olympus TJF 160 R
|
35
|
31/35
|
6/35
|
4/35
|
|
Total
|
102
|
92/102
|
21/102
|
10/102
|
Different microbial species were isolated from contaminated tips and working channels
after manual reprocessing. The organisms most often isolated from the reprocessed
tips were Klebsiella spp. (34 %), Candida spp. (17 %), Serretia spp. (13 %), Pseudomonas spp. (8 %) and Staphylococcus spp. (8 %), while non-albicans Candida spp. (41 %), Pseudomonas spp. (25 %) and Staphylococcus spp. (16 %) were the organisms most often recovered from the reprocessed working channels
([Table 2]).
Table 2
Number of microorganism types identified from the side-view endoscopes before and
after manual reprocessing.
|
Microorganisms
identified
|
Before reprocessing
|
After reprocessing
|
|
Swabs
|
Swabs
|
Normal saline Sample
|
|
Direct
|
Enriched
|
Direct
|
Enriched
|
Total
|
Total
|
|
Streptococcus spp.
|
28
|
28
|
1
|
–
|
1
|
–
|
|
Staphylococcus spp.
|
18
|
20
|
1
|
2
|
2
|
2
|
|
Escherichia spp.
|
31
|
35
|
1
|
1
|
1
|
–
|
|
Klebsiella spp.
|
36
|
36
|
2
|
8
|
8
|
1
|
|
Serretia spp.
|
4
|
6
|
–
|
3
|
3
|
1
|
|
Proteus spp.
|
6
|
7
|
–
|
2
|
2
|
–
|
|
Pseudomonas spp.
|
19
|
21
|
–
|
2
|
2
|
3
|
|
Candida spp.
|
10
|
6
|
–
|
4
|
4
|
5
|
|
Citrobacter spp.
|
6
|
1
|
–
|
–
|
–
|
–
|
|
Yersinia spp.
|
8
|
1
|
–
|
–
|
–
|
–
|
|
Enterobacter spp.
|
10
|
4
|
–
|
–
|
–
|
–
|
|
Total
|
176
|
165
|
5
|
22
|
23
|
12
|
After reprocessing, multiple microorganisms were found from contaminated tips after
4/102 sampling procedures (4 %) and from contaminated working channels after 2/102
sampling procedures (2 %). On one occasion Klebsiella spp. was grown four times from the same scope after reprocessing for four times (all
these samples were collected and processed on the same day). In yet another occasion
Klebsiella spp. and Pseudomonas spp. were isolated from the tip and the working channel of the same side-view endoscope.
Discussion
Over 400 ERCP procedures are performed annually at the tertiary referral endotherapy
unit at the Colombo South Teaching Hospital, Sri Lanka. To minimize the risk of transmission
of infections to patients undergoing ERCP, there is strict adherence to the manual
reprocessing methods for side-view endoscopes that are recommended by the manufacturer.
Procedural errors in cleaning and disinfection of endoscopes have been documented
as the cause for failure of reprocessing in other countries even after the instruments
have been subjected to full reprocessing cycles [9].
To the best of our knowledge, this is the first study carried out in Sri Lanka to
objectively analyze the level of disinfection concerning therapeutic side-view endoscopes.
We used environmental culturing of samples from the tips and working channels of side-view
endoscopes as surrogate markers to monitor the effectiveness of cleaning and disinfection
techniques in a tertiary referral endotherapy unit. Briefly, the manual reprocessing
protocol includes pre-cleaning, manual cleaning, high level disinfection (HLD) using
0.35 % peracetic acid, and rinsing with filtered water after HLD. In this study we
have only sampled the working channel and the tip of the endoscope. According to the
published literature, other channels including auxiliary water channels and air/water
channels can be contaminated during the procedure and reprocessing is recommended
[19]. The internal lumen of the TJF 160 R model’s elevator wire channel is also exposed
to contamination. However the published literature shows that the working channels
and the tips of endoscopes are the sites most likely to be contaminated during the
ERCP procedure [18].
Microbial growth was seen in 20 % of the samples taken from the tip and 9 % of the
samples taken from the working channels of reprocessed side-view endoscopes. The isolation
rate found in this study was less than that of a previous study done in Korea, in
which a 37.2 % culture-positive rate was reported [20]. The majority of bacteria identified from the reprocessed side-view endoscopes in
our study were Gram-negative bacilli and the findings are similar to those of a study
done by Rerknimitr et al. [21]. Candida spp. was the species most often isolated from the reprocessed working channels in
the current study. But Pseudomonas species and Acinetobacter species were the predominant isolates from working channels according to a study by
Moses et al. [22]. We identified that Klebsiella spp. as the species most commonly isolated from the tip of the reprocessed side-view
endoscopes. Isolation of Klebsiella after reprocessing indicates a risk of patient-to-patient disease transmission; Klebsiella pneumoniae has been identified as a cause for duodenoscope-related nosocomial infection in hospitals
in France [23].
The results of our study suggest that disinfection of the tip of the side-view endoscope
using manual reprocessing methods was less effective than disinfection of working
channels. In 2011 Kim et al. [24] found 4.65 % and 0 % culture-positive rates for the endoscope tip and working channel
after automated reprocessing using orthophthalaldehyde disinfectant. This comparison
highlights the complexity of the tip of side-view endoscopes with regard to reprocessing,
even with automated techniques.
We also observed that in only 80 % of instances were the bacteria isolated after reprocessing
the same as those found before reprocessing. This supports the hypothesis that the
present protocol prescribed for manual reprocessing of side-view endoscopes is suboptimal.
If, on 20 % of occasions the organisms identified after reprocessing had not been
present before reprocessing, then they may have come from the environment, from handling
or from the washing reagent.
Interestingly we have investigated the rinsing solution (filtered water) used for
reprocessing; this was found to be sterile on all the occasions. Thus the contamination
may have come from the environment or from handling.
Sampling the working channels before reprocessing was not practically possible because
of time limitations and the availability of only two working sideview endoscopes.
This study was carried out in the only tertiary referral endotherapy unit in Sri Lanka
serving for at least 15 patients per session and therefore having an extremely tight
schedule between one patient and the next. However we sampled the tip of the endoscope
because this did was not take much time.
Reprocessing is a multistep process; involving both humans and chemicals, hence multiple
errors are possible [21]. Although traditional reprocessing methods are still used in clinical practice;
new technologies with HLD are now widely available [25]. Automated reprocessing is universally recommended by several organizations since
it provides a standardized validated reprocessing cycle for clinical settings [26]
[27]. Although there are financial constraints associated with automated reprocessing,
the bioburden found in this study would have been significantly less if automated
reprocessing had been used rather than manual cleaning. Furthermore, there would have
been less human variability and compliance with guidelines would have been better
with automated reprocessing.
Disinfection of flexible endoscopes is less effective without adequate manual cleaning
because of ineffective contact and penetration of disinfectant in the presence of
organic materials [28]
. Insufficiently cleaned endoscope channels can promote the formation of microbial plaques
and biofilms. Hence, correct manual cleaning is important to remove the organic material
which otherwise can fix and promote biofilm formation [17]. Bacterial biofilms contribute to the failure of adequate reprocessing of endoscopes.
Biofilms are resistant to most available disinfectants; hence appropriate reprocessing
of endoscopes using high level disinfectants is recommended [3]. Moses et al. reported that their culture-positive rate was as high as 14.5 % and
they have suggested that faulty mechanical cleaning might have been a possible reason
for the failure of the reprocessing procedure [22].
In the endotherapy unit where the present study was carried out, 0.35 % peracetic
acid is used as a high level disinfectant for reprocessing. Peracetic acid is a powerful
oxidizing agent that rapidly kills a wide range of microorganisms and is active against
a broad spectrum of microorganisms including bacteria, viruses, mycobacteria, fungi,
yeast, and spores of bacteria [16]. Although the exposure time for peracetic acid is 5 minutes for decontamination
of gastrointestinal endoscopes in routine practice, the exposure time for side-view
endoscopes has been extended to 10 min in current practice, to achieve sporicidal
activity. Despite the 10-minute exposure to disinfectant while reprocessing, a considerable
culture-positive rate for reprocessed side-view endoscopes was observed. The effects
of peracetic acids on biological deposits (propensity to fix or to remove biofilms
from material) have not been completely studied [3].
It is recommended that dedicated work areas should be used for reprocessing to avoid
possible cross-contamination [27]. However, in the present study the entire reprocessing procedure was carried out
in the same room where ERCP was done. This could further contribute to the high culture-positivity
rate.
It was found that 71 % (15/21) of the culture-positive samples were taken from the
tip of the 1-year-old and more frequently used side-view endoscope (Olympus TJF Q
180V), used 67/102 times. This compared with 29 % (6/21) of the culture-positive samples
being taken from the 5-year-old less frequently used endoscope (Olympus TJF 160 R),
which was used 35/102 times. This observation is also supported by other studies where
they have found a higher bioburden associated with the frequent use of endoscopes
[29]. In the study only two endoscopes that were currently in use at the endotherapy
unit at the tertiary care hospital were studied. The results might have been different
if more endoscopes had been included, depending on user frequency of use.
Microbiological monitoring can be used to identify deficiencies in reprocessing practices
and also to implement corrective actions that will improve future reprocessing efficacy.
It was a limitation of this study that viruses and possible uncultivable bacteria
were not considered. Thus the real bio burden after reprocessing might have been underestimated.
The specimen processing method used in the study would have its own limitations in
determining the true bioburden in comparison with the filtration method. However this
specimen processing method for detection of the bioburden in endoscopic working channels
has been used in several published studies [11].
In conclusion, as high culture-positive rates were observed after reprocessing using
the standard manual reprocessing techniques, further investigations with more scopes
in different centers on the effectiveness of endoscope reprocessing is needed to rectify
reprocessing methods to prevent transmission of infection secondary to ERCP.
