Microbiological surveillance result of endoscopes after INTERCEPT Foam Spray: a quasi-experimental pilot study in Singapore
Article information
Abstract
Background/Aims
This study aimed to assess the impact of INTERCEPT Foam Spray (IFS) application on delayed endoscope reprocessing through microbiological surveillance culture (MSC).
Methods
A quasi-experimental, matched-comparison pilot study was conducted using gastrointestinal endoscopy. IFS was applied to the endoscopes after precleaning and before reprocessing the next day. An equal number of endoscopes, matched by endoscope type, were subjected to routine reprocessing. The MSC were subjected to high-level disinfection to detect any contamination. Data were analyzed using the chi-square test or Fisher exact test (categorical data) and Student t-test (continuous data).
Results
In total, 150 MSCs were collected from 42 endoscopes. Positive MSCs were observed in 4.0% (4/75) of the sprayed group and 1.3% (1/75) of the control group (95% confidence interval, 30.34–0.31; p>0.05), all of which were contributed by colonoscopes. Colonoscope were more prone to positive MSC (mean difference in percentage, p<0.05). Mean spraying hours were not associated with detected growth (11.7% vs. 13.6%; 95% confidence interval, 1.43 to –5.27; p>0.05), with environmental and skin flora being the primary contaminants.
Conclusions
IFS may be applied when delayed endoscope processing is necessary, but with caution when applied to colonoscopes. However, further research is warranted to verify the result.
INTRODUCTION
Currently, flexible endoscopes are required to undergo complex reprocessing after use: precleaning (bedside cleaning), leak testing, brushing, rinsing, visual inspection, high-level disinfection (HLD), drying, and storage.1-4 Failure in any of these steps leads to inadequately reprocessed endoscopes, and recent studies have reported infection outbreaks caused by breaches in reprocessing protocols.5-9
Endoscope-associated nosocomial can develop despite adherence to reprocessing protocol.10 A major contributing factor is biofilm formation within endoscope channels,11-14 where they can persist even in completely reprocessed endoscopes.11 After use, humid pockets inside channels permit the growth of microorganism communities, where microorganisms attach themselves to inner channel surfaces and produce extracellular polymeric material, forming a resistant matrix against HLD.15,16 Such protection can also extend to sensitive indicator pathogens during biocidal actions, enabling their persistence in the environment.17 Delays in manual cleaning, inadequate drying, improper storage, and endoscope inner channel damage promote biofilm formation within the endoscope channels and parts.18,19 Particularly, delayed manual cleaning was reported to harden the bioburden, thus reducing the cleaning and disinfection effect.20
To effectively reprocess contaminated endoscopes, national and manufacturer guidelines recommend manual cleaning immediately or within an hour after use.1,2,4,20 According to Society of Gastroenterology Nurses and Associates, manual cleaning is the most critical step in endoscope reprocessing,13 with proper cleaning alone being capable of 6 log reductions in microbial load.21 However, clinical situations such as delayed transportation and staff shortages may not always allow timely reprocessing. For this purpose, Bromiley tested the INTERCEPT Foam Spray (IFS, Cantel Ltd.), which is designed to increase manual cleaning delay for up to 72 hours in endoscope reprocessing.22 Efficacy results showed, in comparison to un-conditioned endoscopes, the IFS achieved 6 log reduction of test bacteria (Pseudomonas aeruginosa), apart from preventing biofilm formation and hardening of bioburden by keeping the endoscope in moist conditions for 72 hours.22 In contrast to endoscopes that underwent manual cleaning after a 1-hour delay, reprocessing of conditioned endoscopes also attained more extensive bacterial reduction and biofilm prevention.22
Despite the potential reduction in labor and cost demands and improved workflow with the use of IFS, there is currently limited evidence supporting its routine application in standard clinical practice. We conducted a quasi-experimental pilot study at a local hospital to evaluate efficacy of IFS and its effect on delayed endoscope reprocessing. The first objective of this preliminary study was to assess the effectiveness of IFS in keeping endoscopes in a pre-cleaned state beyond the 1-hour recommendation. Hence, endoscopes used out-of-hours were recruited to achieve the longest possible delay while minimizing interruptions to clinical work. As a pilot study, the team aimed to test the study's recruitment rate to inform further research on endoscopic reprocessing.
METHODS
Settings
The study endoscopy unit performs a wide range of procedures annually (approximately 10,000 procedures). Given financial constraints and to minimize clinical interruption, the team adopted a prospective, quasi-experimental matched control approach, with a study period between April 2021 and December 2021.
Sampling strategy
1) Inclusion and exclusion criteria
A group of gastrointestinal scopes: GIF-HQ290, GIF-H290, GIF-FQ260Z, GIF-2T240, CF-HQ290L, CF-H290L, PCF-H290L, TJF-260, JF-260, GF-UCT260 (Olympus) in circulation (total 54) in the endoscopy unit were included in this study. Endoscopes in service and those that were limited in number were also excluded. All endoscopes had 1 month to 6 year’s-service.
2) Sample size
As this was a pilot quasi-experimental study, 150 samples were collected without sample size calculations. Samples were equally split into two groups: the sprayed (SP) group and the control group.
3) Sampling method
Whenever the following day was a working day, the flexible endoscopes used for emergency cases after office hours were used in the SP group. SP endoscopes were immediately pre-cleaned (bedside cleaning) after withdrawal from the patient using 0.25% INTERCEPT before spraying with IFS. They were then placed inside the scope trays and covered with a twinfoil plastic cover (Cantel Ltd.). The SP endoscopes were subsequently subjected to routine endoscope reprocessing on the following day. The exact number of endoscopes matched by the endoscope type was later selected, reprocessed within an hour after use, and assigned to the control group. Control recruitment occurred on any working day according to the prevailing clinical situation.
(1) Endoscope reprocessing process
The IFS was first removed from the SP endoscopes using gauze. Subsequent reprocessing proceeded in this manner: leak testing by Viriscan (Cantel Ltd.), manual cleaning of air and water channels, biopsy channels, and auxiliary channels (if applicable) with brushing six to ten times using a pull-through (Cantel Ltd.) and channel brush (Olympus). After brushing, endoscopes were flushed with freshly prepared 5% INTERCEPT and rinsed with water using Scope Buddy (Cantel Ltd.). The external surfaces of the endoscopes were rinsed with running-filter tap water. Visual inspection was conducted before placing the samples in an automated endoscope repressor (AER) to undergo HLD (Cantel Ltd.). Double HLD (DHLD) was performed for all endoscopes used in contagious cases, such as carbapenem-resistant Enterobacteriaceae human immunodeficiency virus, Hepatitis B and C, methicillin-resistant Staphylococcus aureus, to comply with the current flexible endoscope reprocessing policy. Control endoscopes underwent bedside cleaning in which gastroscopes and colonoscopes were purged with 0.25% INTERCEPT for at least 10 seconds while duodenoscopes for 30 seconds, followed by leak testing, manual cleaning process within 1 hour and the same steps as the SP group except for applying and removing the INTERCEPT Foam.
(2) Microbiological surveillance culture procedure
After completing the AER cycle, the microbiological surveillance culture (MSC) test was performed using the brushing-flushing method for all endoscope channels. The endoscope channels were connected to sterilized reusable endoscope-cleaning tubing. Sterile 0.9% sodium chloride (0.9% normal saline, NS) was flushed into the endoscope channels using a 20 mL sterile syringe into each channel (biopsy channel, air/water channel, and auxiliar/elevator channel, if applicable) and collected at the distal tip of the endoscope using a sterile specimen bottle. If applicable, an additional reusable sterile tube was connected to the elevator port to flush through a 100 mL sample. The distal tips of the endoscopes used in the contagious cases were swabbed, collected, and placed into a specimen tube (COPAN). All MSC tests were conducted aseptically to prevent potential cross-contamination. The MSC samples were immediately dispatched for analysis to reduce the potential proliferation of microorganisms.
(3) Laboratory procedure
Each sample of endoscope flush water was processed using the disposable EZ-Fit Filtration unit (Millipore SAS) with the EZ-Stream pump and manifold system. The disposable cellulose membrane was removed from the filtration unit and placed on a Tryptone Soy Agar plate (Thermo Scientific). Agar plates were incubated at 35 ℃ in ambient air and examined daily for up to 2 days. Colonies growing during this period were identified using (matrix-assisted laser desorption/ionization-time of flight) (Bruker Daltonics). Klebsiella pneumoniae carbapenemase, imipenemase, oxacillinase-48, New Delhi metallo-β-lactamase, and Verona integron-encoded metallo-β-lactamase carbapenemase production in the Enterobacterales colonies was determined using the CARBA-5 test (NG Biotech).
Result interpretation
A microorganism threshold was developed to guide the decision of positive or negative MSC results: colony forming unit (CFU) equal to or greater than 10 or the identification of any critical microorganism was considered positive (Supplementary Table 1). Additionally, the carbapenem-resistant Enterobacteriaceae swab results were combined with the environmental culture as a single MSC. Therefore, if the swab result is negative and the environmental result is positive, the MSC result from the endoscope would still be considered positive, and vice versa.
Data collection
MSC results were obtained from the hospital laboratory once available. The results were then hand-copied to the study files by a research assistant. Two other research assistants independently transferred the results to the original laboratory copy and research computer weekly. The two research assistants verified all the results once all MSC results were available. Finally, the principal investigator rechecked all data before the analysis.
Data analysis
For the primary outcome, the chi-squared test (Microsoft 365 ver. 2016) or Fisher exact test (Free Statistic Calculators ver. 4.0), whichever was applicable, was used to compare the positivity rate between groups. Fisher exact test was also used to detect the types of endoscopes that were more prone to positive MSCs. A simple Student t-test (Microsoft 365 ver. 2016) was used to determine any association between the SP group’s spraying hours and cfu counts. 95% confidence interval was calculated based on the log odds ratio and then transformed back to odds ratio by taking exponential.
Ethical statement
Ethical approval was waived by the National Health Group of Singapore (NHG DSRB; Ref:2021/00090).
RESULTS
During the study period, 150 MSCs (n=150), with 75 samples from each group, were collected from 25 gastroscopes, 12 colonoscopes, and four duodenoscopes. The endoscope model distributions are presented in Table 1. Overall, MSCs obtained from both groups did not show any statistically significant differences. Growth was observed in 17 (24.0%) and 18 (22.7%) samples collected from the SP and control groups, respectively (95% confidence interval [CI], 2.30–0.51; p>0.05) (Table 2). There were three out of 75 MSCs with positive growth (4%) in the SP group, in contrast to one out of 75 MSCs (1.33%) in the control group (95% CI, 0.31–30.34; p>0.05). Notably, there were a total of 40 samples collected after DHLD (19 from SP and 21 from control) from all types of gastrointestinal endoscopes, with only 1 positive MSC found in the control group. The result was not significant compared to that from single cycle of HLD (SHLD) (3/110) (p>0.99), in which three positive MSCs were found. Growth was 9/40 (DHLD) vs. 22/110 (SHLD) (p>0.05).
Distribution of flexible endoscope models between the sprayed group and control group
Overall growth detected between the sprayed and control group
Positive growth was only detected in colonoscope samples, with three positive samples from the SP group when compared to those from the control group (Table 3). Colonoscopes were found to be more prone to positive MSCs than gastroscopes and duodenoscopes (p<0.001). Further stratified analysis was not conducted because of the small number of samples with positive growth or any growth.
Analysis of positive growth and any growth based on the total samples collected from gastroscopes, colonoscopes, and duodenoscopes
The time between spraying and reprocessing (sprayed hours) was also analyzed according to the MSC results. Altogether, hours ranged from 4.83 to 24.5 hours, with a median of 10.92 hours and an interquartile range (IQR) of 9.00–13.25 hours (Table 4). The data for both groups were rightly skewed (Fig. 1), with a difference in spraying hours between endoscopes with and without growth (p>0.05, calculated as unequal variance). Endoscopes with growth registered a higher mean (13.6 vs. 11.7 hours), median (11.09 vs. 10.92 hours) and IQR (9.13–18.78 vs. 9.17–13.5 hours) as compared to those without.
Relationship between sprayed hours and microorganisms detected in colony forming unit
Boxplot of sprayed hours for samples with growth and without growth.
The most commonly observed organisms were environmental contaminants or skin flora: Bacillus species (spp.) including Bacillus cereus, Bacillus simplex, and Micrococcus luteus (Fig. 2). All positive MSCs identified were due to more than ten cfu of microorganisms instead of high-concern pathogens, according to the hospital laboratory MSC response protocol (Supplementary Table 1). As pathogens such as P. aeruginosa, Klebsiella pneumoniae, and other gram-negative rods were not detected in the duodenoscopes, no remedial action was required. No further comparisons between the study groups were made because most endoscopes showed no growth.
Frequency of detection of microorganisms among gastroscopes and colonoscopes between study groups.
DISCUSSION
This study aimed to evaluate the effectiveness of IFS using flexible endoscope MSC. Overall, there was no significant concern about the sprayed endoscopes, indicating that the IFS spray may play a role in flexible endoscope reprocessing.
Flexible endoscopes should be kept as dry as possible throughout reprocessing and the preparation stage for clinical use.4,13 Dry conditions are critical in preventing biofilm formation and reducing the risk of hospital-acquired infection,18 and excessive drying before manual cleaning can lead to the hardening of the bioburden, potentially reducing the efficacy of the subsequent disinfection steps.23 However, logistical issues such as transportation or staff shortages in clinical settings may sometimes result in unavoidable reprocessing delays. The current recommendation is to follow the manufacturer's protocol for delayed cleaning and disinfection,13,23 which involves immersing gastrointestinal endoscopes in a suitable dilute detergent solution for at most 10 hours.20 In comparison, IFS is advertised to afford delays in reprocessing for up to 72 hours while preventing overdrying and facilitating detachment of the bioburden.22
IFS is a surfactant-based, non-enzymatic formulation containing quaternary ammonium compounds (QAC).22 QAC is a type of low-toxicity, cationic biocide widely employed as an active antibacterial agent in commercial disinfectants for healthcare facilities.24 It can exert powerful antibiofilm properties at low concentrations through cell lysis, preventing microbial surface adhesion and biofilm maturation.25 Antibiofilm efficacy of QACs on high-concern organisms such as Staphylococcus aureus, P. aeruginosa, Salmonella spp., Escherichia coli, and Acinetobacter spp. has been previously demonstrated.24 Although there is widespread adoption of IFS in delayed endoscope reprocessing, it has yet to be intensively and rigorously studied.
The current study found no significant differences in MSC results after IFS application compared to routine practice. Prolonged detergent contact did not result in a more positive growth than the standard practice (p>0.05). In an in vitro study, IFS was able to reduce biofilm formation and achieve more than 6 log reductions (cfu/mL) of P. aeruginosa after 72 hours.22 After overnight enzymatic detergent soaking, Ofstead et al.26 demonstrated negative MSC results from 8 gastroscopes and colonoscopes. Non-enzymatic detergent has a similar effect on biofilm removal and viable detection of enzymatic detergent.27
In this study, although more growth was observed as sprayed hours increased (zero growth: 11.7 hours vs. any growth: 13.6 hours), it was not significant (p>0.05). A definite relationship between spraying duration and detectable growth could not be established owing to the small sample size and study design. Nonetheless, given that this was a real-world study, the results may provide insights into clinical applications and future study directions. IFS may be an alternative to the delayed reprocessing protocol with regular MSC and preventive maintenance to monitor the long-term impact. Given that the maximum soaking time allowed with IFS application is 72 hours, future studies should be undertaken on a larger scale, focusing on longer soaking times (more than 24 hours but less than 72 hours) for conclusive results.
Additionally, the MSC results from our current study were comparable to those of previous studies; overall, positive MSCs were detected in 1.3% of control and 4.0% of SP, and zero growth was detected in all duodenoscopes. Ma et al.28 detected contamination in 1.1% (3/285) duodenoscope post-HLD. Another report showed a range of 0.8% to 9.1% positive MSC rate from 1,931 MSCs of different types of gastrointestinal endoscopes.29 An earlier study demonstrated that duodenoscope undergoing double manual cleaning and DHLD resulted in 4.9% (38/783; 95% CI, 3.5%–6.6%) positive culture.30 The enhanced endoscope reprocessing measures we adopted may explain our study's low positive MSC rate. Double manual cleaning and DHLD were implemented in our daily practice and reprocessing policy in 2019 to ensure effective flexible endoscope reprocessing. Meticulous manual cleaning (with mechanical friction) is the most effective method for removing bioburdens and biofilms.4,31 DHLD was recommended by the U.S. Food and Drug Administration in 2015 to achieve better flexible reprocessing outcomes. Our low MSC rate may indicate that the current reprocessing practices were adequate. During the study period, thorough reprocessing was employed to render endoscopes safe for patient use, double-channel brushing was applied to all endoscopes, and double AER cycles were adapted for duodenoscopes and endoscopes used in infectious cases.
However, studies have not favored DHLD over SHLD on duodenoscopes or linear echoendoscopes. A recent large RCT showed a duodenoscope contamination rate of 4.2% (127/3,052) after DHLD versus 3.9% (108/2,798) after SHLD (p=0.64).32 Another randomized comparison study also demonstrated that 4.1% (7/169, DHLD) versus 2.3% (4/174, SHLD) duodenoscope had 10 or more cfu (p>0.05).33 In our current study, positive growth or any growth from endoscopes that underwent DHLD was not significant compared to those that underwent SHLD. Therefore, it is difficult to conclude that the low positivity rate was attributable to DHLD.
On another hand, as mentioned earlier, positive culture of reusable endoscope is largely contributed by biofilm within the endoscope channels even after adequate reprocessing.11-14,27,34-41 The good news is that meticulous channel brushing with detergent can significantly remove both traditional biofilm and build-up biofilm, thus ensuring the effectiveness of HLD.42 With a contact time of 1 minute, INTERCEPT is able to remove 100% protein and >99% of carbohydrate and can reduce 7.21 log of viables from biofilm.43 Additionally, high speed flushing of detergent can also slow down biofilm generation.41 A study showed that after 3 minutes lavage at the rate of 250 mL/min with 0.5% INTERCEPT, there were no viables detected from the Teflon tube (endoscope material) which was contaminated with 106 log of E. coli. No obvious biofilms were observed by electron microscopy, whereas large amounts of bacterial sediment were observed in the broth bottle after 72 hours. Biofilms became very loose with the high shear force created by INTERCEPT.44 It was found that P. aeruginosa biofilm achieved more than 8 log reduction of viables after 10 seconds flushing with 500 mL of INTERCEPT.45 In our study, endoscopes underwent a few rounds of INTERCEPT detergent high speed purging during reprocessing: 250 mL over 10 seconds or 500 mL over 30 seconds, more than 1 L over 1 minute through ScopeBuddy, and 5 L over 2 minutes during AER cycle. Subsequently, the standard AER disinfectant cycle removed most of the viables.42,46 From this perspective, the effect of DHLD was not significant.
However, the current study also agreed that there were no bacterial-free endoscopes even after meticulous cleaning, and appropriate HLD11 detected viables after a few rounds of reprocessing because of the build-up biofilm within endoscope channels, which is difficult to eliminate and may cause patient infection,27,35,36,38 especially in biofilms within the air/water channel and the air/water junction. This was showed by Ren-Pei and colleagues that 76.9% (10/13) of air/ water channels were contaminated with obvious biofilm compared to 54.6% (36/66) of suction and biopsy channels.47 Primo et al.38 detected that 18/28 endoscope channels were stained with mixed bacterial of build-up biofilm after 30-60 days of clinical use from Scanning electron microscopy. Researchers explained that the sheer force of irrigation without friction from manual and auto cleaning are not sufficient to eliminate mature biofilm and bioburdens.
Overall, INTERCEPT is effective to remove biofilm during cleaning, on top of the thorough endoscope channel brushing. From this point, since the IFS was applied to the exterior surfaces of endoscope, it is difficult to distinguish the impact of INTERCEPT detergent and the IFS because of the low positive results that were observed from both groups.
The current study showed that colonoscopes was more prone to positive results than gastroscopes and duodenoscopes (p<0.001). Similar findings have been reported in other studies. Suction and biopsy channels had 20% (1/5) contamination in gastroscopes compared to 83.3% (5/6) in colonoscopes after HLD.26 Biopsy channel contamination rate from colonoscopes (20.8%, 25/120) was significantly higher than gastroscopes (10.7%, 32/300) (p<0.05).48 Significantly higher than gastroscopes and duodenoscopes, three colonoscopes had >100 cfu counts compared to one gastroscope.49 This might be due to the nature of the endoscope procedure involved, whereby colonoscopes carry more bacteria than upper gastrointestinal endoscopes do. However, these results were consistent with those of previous studies. The earlier mentioned study showed no difference in their Phase II study among different types of endoscopes.49 Moreover, the study by Chen and colleagues also showed 2.0% (15/765) contamination of gastroscopes, 1.9% (14/730) for colonoscopes, and 0.8% (3/379) for duodenoscopes.29 But the result from Decristoforo et al.49 was limited by the small sample size and study design. The differences observed by Chen et al.29 were not significant. Thus, it was difficult to generate a conclusion. In addition, sampling and culturing techniques may play a decisive role in the recovery of viable bacteria and the interpretation of results.3,15,50,51 From the previously mentioned studies, Chen et al.29 mainly employed flushing of endoscopes with 100 mL distilled water for culturing, while Decristoforo et al.49 utilized flushing or brush-flushing with 20 mL of 0.9% NS.49 In our study, 100 mL of 0.9% NS flushing was applied. Various laboratory analyses were performed. However, further studies are required to draw concrete conclusions.
The microorganisms discovered in our study were commonly isolated and were consistent with those reported in other studies. Although high-concern pathogens (Supplementary Table 1) were recovered from both groups, they were not detected at high cfu counts (Fig. 1, Table 5). Endoscopes with positive growth were cleared after another round of the reprocessing cycle (all double brushing and DHLD), except for one colonoscope that had six years of service. This particular colonoscope was subsequently found to have inner channel damage, was removed from service, and sent for repair. Inner-lumen damage is known to result in MSC positivity. 8,26,52,53 The loss in the endoscope's inner surface integrity compromised the reprocessing efficacy, rendering it inadequate, especially if there was prior biofilm formation and build-up.54 On the other hand, our current study also confirmed that the present endoscope reprocessing process cannot produce bacteria-free endoscopes.10,32,33 Inner channel examination of flexible endoscopes should be routinely conducted to detect any damage or defect to reduce positive MSC and potential cross-contamination.52 Therefore, endoscope redesign, sterilization, and single-use endoscopes with the consideration of cost-effectiveness may be the solution to eliminate endoscope-related hospital-acquired infections.55-57
In conclusion, the current study confirmed the feasibility of the out-of-hour use of IFS. Overall, no significant differences in the MSC results were observed between flexible endoscopes that underwent IFS application with delayed manual cleaning and those that adhered to the standard recommended practice. Moreover, when flexible endoscopes were sprayed for 24 hours in a sealed condition, longer spraying times did not result in significantly higher cfu counts. Colonoscopes were more prone to have positive growth than did gastroscopes and duodenoscopes. However, the long-term impact of IFS on the endoscope warrants large-scale studies and prolonged observation.
Supplementary Material
Supplementary Table 1. Response to positive flexible endoscope culture.
Supplementary materials related to this article can be found online at https://doi.org/10.5946/ce.2024.030.
Notes
Conflicts of Interest
The authors have no potential conflicts of interest.
Funding
None.
Acknowledgments
The authors would like to thank all staff, especially those who worked in the endoscope reprocessing area of the Ng Teng Fong General Hospital Endoscopy Centre. This requires great individual commitment to achieve teamwork. We also thank all other professionals involved in this study for their indirect contributions.
Author Contributions
Conceptualization: CW, RZ; Data curation: CW, RF, JL; Formal analysis: RD, CW; Supervision: RZ, XM, CC; Validation: CW, RZ; Writing–original draft: CW; Writing–review & editing: all authors.