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Assessment of postmanual cleaning adenosine triphosphate tests to prevent the use of contaminated duodenoscopes and linear echoendoscopes: the DETECT study
Department of Gastroenterology and Hepatology, Erasmus MC University Medical Centre, Rotterdam, The NetherlandsDepartment of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Centre, Rotterdam, The Netherlands
Reprint requests: Marco J. Bruno, MD, PhD, Department of Gastroenterology and Hepatology, Erasmus MC University Medical Centre, PO Box 2040, 3000 CA Rotterdam, The Netherlands.
Affiliations
Department of Gastroenterology and Hepatology, Erasmus MC University Medical Centre, Rotterdam, The Netherlands
We investigated whether the use of postmanual cleaning adenosine triphosphate (ATP) tests lowers the number of duodenoscopes and linear echoendoscopes (DLEs) contaminated with gut flora.
Methods
In this single-center before-and-after study, DLEs were ATP tested after cleaning. During the control period, participants were blinded to ATP results: ATP-positive DLEs were not recleaned. During the intervention period, ATP-positive DLEs were recleaned. DLEs underwent microbiologic sampling after high-level disinfection (HLD) with participants blinded to culture results.
Results
Using 15 endoscopes of 5 different DLE types, we included 909 procedures (52% duodenoscopes, 48% linear echoendoscopes). During the intervention period, the absolute rate of contamination with gut flora was higher (16% vs 21%). The main analysis showed that contamination was less likely to occur in the intervention period (odds ratio, .32; 95% credible interval [CI], .12-.85). A secondary analysis showed that this effect was based on 1 particular duodenoscope type (estimated probability, 39% [95% CI, 18%-64%] vs 9% [95% CI, 2%-21%]), whereas no effect was seen in the other 4 DLE types. In detail, of the 4 duodenoscopes of this type, 2 had lower contamination rates (69% vs 39% and 36% vs 10%). During the control period, both these duodenoscopes had multiple episodes with ongoing contamination with the same microorganism that ended weeks before the start of the intervention period (ie, they were not terminated by ATP testing).
Conclusions
Postmanual cleaning ATP tests do not reduce post-HLD gut flora contamination rates of DLEs. Hence, postcleaning ATP tests are not suited as a means for quality control of endoscope reprocessing.
Many of these were outbreaks with multidrug-resistant organisms. In several of these outbreaks, it was shown that duodenoscopes were already contaminated for months before transmission was discovered with attack rates (ie, number of infected or colonized cases/number of exposed persons) up to 40%.
Successful control of an endoscopic retrograde cholangiopancreatography–associated nosocomial outbreak caused by Klebsiella pneumoniae carbapenemase producing Klebsiella pneumoniae in a University Hospital in Bogota, Colombia.
the published number of 490 patient infections and 32 deaths because of contaminated duodenoscopes between 2008 and 2018 is considered an underestimation.
After each procedure, endoscopes are reprocessed. This process, which includes flushing, manual cleaning, high-level disinfection (HLD), and drying, has little margin for error.
Studies on the bioburden on medical devices and the importance of cleaning. Disinfection, sterilization and antisepsis: principles and practices in healthcare facilities.
Association for Professionals in Infection Control and Epidemiology,
Washington, DC2001: 63-69
Implementation of remote video auditing with feedback and compliance for manual-cleaning protocols of endoscopic retrograde cholangiopancreatography endoscopes.
Duodenoscopes and linear echoendoscopes (DLEs) are more difficult to clean than other endoscopes because of their complex design, which includes a side-viewing tip, forceps elevator, and elevator wire channel. Even when manufacturers’ instructions for use were strictly followed, large outbreaks have occurred.
Because current reprocessing techniques do not achieve reliable decontamination, patients undergoing ERCP are regularly exposed to contaminated duodenoscopes. Duodenoscope manufacturers’ postmarket studies show a 5.4% contamination rate with indicator microorganisms associated with disease transmission (ie, Escherichia coli, Pseudomonas aeruginosa),
Patients undergoing EUS may also be exposed to contaminated equipment, as indicator microorganism contamination rates of linear echoendoscopes range between 1.1% and 8%.
Gastroenterology, microbiology, and regulatory agencies have stressed the need for easy to implement and effective control measures to check endoscope decontamination.
Prevention of multidrug-resistant infections from contaminated duodenoscopes: position statement of the European Society of Gastrointestinal Endoscopy (ESGE) and European Society of Gastroenterology Nurses and Associates (ESGENA).
However, culturing is labor intensive and expensive and gives delayed feedback because of the 48- to 72-hour incubation period. Real-time audits of “bacterial load” during reprocessing could drastically improve endoscope safety. The most often proposed alternative is the use of the adenosine triphosphate (ATP) assay, a test originating from the food industry and recently introduced into hospitals to monitor cleanliness of the environment. The ATP test is a bioluminescence assay using luciferase-catalyzed oxidation of luciferin causing ATP-dependent emission of light, measured in relative light units (RLUs). Bacteria and human cells and secretions contain ATP, and the presence of ATP after cleaning may indicate organic residue requiring recleaning.
It is unclear whether the use of ATP tests to guide reprocessing prevents the use of contaminated endoscopes. ATP was not found to be useful for testing after HLD because of the poor correlation with terminal reprocessing cultures.
A systematic review of adenosine triphosphate as a surrogate for bacterial contamination of duodenoscopes used for endoscopic retrograde cholangiopancreatography.
Comparison of clinically relevant benchmarks and channel sampling methods used to assess manual cleaning compliance for flexible gastrointestinal endoscopes.
it is essential to scientifically establish the usefulness and clinical value of ATP. Therefore, the aim of this study was to assess whether postcleaning ATP tests, with recleaning in the event of a positive ATP test, lower the number of clinically relevant positive cultures of DLEs.
Methods
From July 2017 to October 2018, we conducted a prospective single-center intervention study in a before-and-after design to assess the utility of ATP testing after manual cleaning. The study was conducted at the 1320-bed tertiary Erasmus MC University Medical Centre in Rotterdam, the Netherlands, which performs approximately 900 ERCP and 750 EUS procedures yearly.
Endoscopes and reprocessing
Multiple DLEs were used throughout the study. Four ED34-i10T duodenoscopes (Pentax Medical, Dodewaard, The Netherlands) were in use until they were replaced by Pentax ED34-i10T2 duodenoscopes with a disposable elevator cap. One ED34-i10T2 was introduced after 7 weeks and 4 after week 40. During the entire study, 2 TJF-160VR duodenoscopes (Olympus, Zoeterwoude, The Netherlands), 3 Pentax EG-3870UTK linear echoendoscopes, and 2 Pentax EG-3270UK linear echoendoscopes were in use. Servicing, maintenance, and loan endoscopes were provided by Pentax and Olympus.
Reprocessing was performed according to manufacturers’ instructions for use and the handbook of the Dutch Steering Group for Flexible Endoscope Cleaning and Disinfection
Advisory Board Cleaning and Disinfection Flexible Endoscopes (SFERD). Professional standard handbook version 3.0. Flexible endoscopes—cleaning and disinfection. 2013 [updated 18-09-2013]. Available at: https://www.infectiepreventieopleidingen.nl/downloads/SFERDHandbook3_1.pdf. Accessed January 30, 2021.
and consisted a bedside flush with water, manual cleaning using Neodisher MediClean Forte cleaning agent (dr. Weigert, Assen, The Netherlands), and HLD using Neodisher Septo peracetic acid in 8 Wassenburg WD440-PT automated endoscope reprocessors (Wassenburg, Dodewaard, The Netherlands). In April 2018, the endoscopy department relocated, and 10 new Wassenburg WD440-PT automated endoscope reprocessors were put in use. In December 2017, the original staff of 4 disinfection assistants was merged with the sterilization unit of 15 members. The existing clinical monthly surveillance cultures were continued during the study; if contaminated with gut flora, endoscopes were quarantined until effectively decontaminated as shown by follow-up cultures.
Study design
This before-and-after study consisted of 2 parts: a baseline control period followed by an intervention period (Supplementary Fig. 1, available online at www.giejournal.org). In both periods DLEs were subjected to postcleaning ATP tests and cultured after HLD by dedicated sampling staff. In the control period, participants were blinded to ATP results: ATP-positive endoscopes were not recleaned. ATP test results were shown to the disinfection assistant only in the intervention period; if positive, the endoscope was cleaned and ATP tested again, with a maximum of 2 repeated cycles. DLEs underwent HLD regardless of the result of a possible positive third ATP test. Sampling staff, disinfection assistants, and researchers were blinded to the study culture results.
The primary endpoint was the reduction of the percentage of DLEs contaminated with gut flora between the control period and the intervention period. We considered the effect of the ATP test as clinically relevant if the gut flora contamination rate was reduced by 50%. Based on Dutch prevalence studies, we estimated an 8% gut flora contamination rate for DLEs,
This required a sample size (power, 80%; α = .05) of 870 procedures. The study was approved by the Erasmus MC Medical Ethical Research Committee (MEC-2017-291); no patients were subject to any study procedures, and no patient data were collected.
ATP tests
Depending on DLE type, 3 to 4 sites were sampled. First, the distal 10 cm of the endoscope, then the forceps elevator, and finally the protection cap (if unsealed and reusable) were swabbed with Clean-Trace ATP surface tests (3M Company, Maplewood, Minn, USA). Finally, 40 mL of sterile water flushed through the biopsy/suction channel was sampled with the Clean-Trace ATP water test. Endoscopes were considered ATP-positive if ≥1 sample tested ≥201 RLUs. This cutoff has been validated for the distal tip and flush
Comparison of clinically relevant benchmarks and channel sampling methods used to assess manual cleaning compliance for flexible gastrointestinal endoscopes.
and also used for the elevator and cap for which this was not the case.
Microbiologic cultures
Depending on DLE type, 3 to 4 sites were sampled. First, the forceps elevator and then the protection cap (if unsealed and reusable) were swabbed with e-Swabs (Copan Italia SpA, Brescia, Italy). Next, the biopsy/suction channels were flushed with sterile physiologic saline solution of which 20 mL was collected in a sterile container at the distal tip. Finally, the biopsy/suction channels were brushed with either Olympus BW-412T or Pentax CS6021T single-use cleaning brushes. Brush tips and e-Swabs were vortexed in e-Swab 1-mL Amies medium of which .75 mL was poured on blood agar. Channel flushes were filtrated over a .22-μm filter, of which the filtrate was forced on R2A agar. Cultures were incubated at 35ºC at 5% CO2 and examined for growth after day 4. Culture results were presented in colony forming units (CFUs)/20 mL per microorganism.
We used 2 contamination definitions: presence of microbial growth (≥1 CFUs/20 mL) of GI microorganisms (gut flora) and microbial growth with ≥20 CFUs/20 mL of any type of microorganism (AM20) as used by the European and Dutch guidelines.
Advisory Board Cleaning and Disinfection Flexible Endoscopes (SFERD). Professional standard handbook version 3.0. Flexible endoscopes—cleaning and disinfection. 2013 [updated 18-09-2013]. Available at: https://www.infectiepreventieopleidingen.nl/downloads/SFERDHandbook3_1.pdf. Accessed January 30, 2021.
Endoscopes could be contaminated according to either or both definitions.
Statistical analysis
To investigate the effect of the intervention on the probability of contamination measured at any of the sampling sites, we fitted Bayesian logistic mixed models taking into account a correlation between repeated measurements of the same endoscope using endoscope-specific (random) intercepts. The models were fitted using the R package JointAI, which performs simultaneous analysis and imputation of incomplete covariates.
We used 2 models. Model 1 was the main analysis, in which we included all covariates potentially influencing reprocessing: study period, study time (per 10 weeks), study procedures (per 50 procedures), transfer to a new endoscopy building, and introduction of new disinfection assistants. Model 2 was used for the secondary analysis, in which we assessed differences between endoscope types by adding the endoscopy type and its interaction with the study period to the model.
Results are presented as posterior means and 95% credible intervals (CIs) of the odds ratios of the covariates. For clinical interpretation of the results of model 2, estimated probabilities were calculated for both study periods, whereas other values were fixed to reasonable reference values. Analyses were performed in SPSS version 23.0 (SPSS Institute, Chicago, Ill, USA) and R version 4.0.3 (Vienna, Austria).
Results
Of 909 procedures, 431 were performed during the control period of 20 weeks and 478 during the intervention period of 45 weeks (Table 1). Of these procedures, 473 were performed with duodenoscopes and 433 with linear echoendoscopes. Supplementary Figure 2 (available online at www.giejournal.org) shows the inclusion and contamination timelines per endoscope type. Eight procedures in which the endoscope used was not known and 6 procedures with unknown ATP test results were excluded from the analyses. Three unknown values for the number of study procedures and 7 missing values pertaining to which disinfection assistant was involved were imputed during the analysis.
Table 1Contamination prevalence of duodenoscopes and linear echoendoscopes
No. of cases
Gut flora
AM20
Duodenoscopes and linear echoendoscopes
Control period
431
16 (67)
34 (145)
Intervention period
478
21 (102)
39 (185)
1 time manual cleaning
315
28 (88)
40 (126)
≥2 times manual cleaning
162
9 (14)
36 (59)
Duodenoscopes
473
30 (143)
59 (280)
Control period
224
27 (61)
60 (136)
Intervention period
249
33 (82)
58 (144)
Linear echoendoscopes
433
6 (26)
12 (50)
Control period
205
3 (6)
4 (9)
Intervention period
228
9 (20)
18 (41)
Values are % (n).
AM20, Microbial growth with ≥20 colony-forming units/20 mL of any type of microorganism.
The main analysis, assessing covariates potentially influencing reprocessing, showed that during the intervention period DLEs were less likely to be contaminated with gut flora (odds ratio, .32; 95% CI, .12-.85) (Fig. 1). However, as shown in Table 1, the DLE gut flora contamination rate was higher in the intervention period (21%; n = 102) than in the control period (16%; n = 67). This difference follows from the performance of 2 distinct duodenoscopes, explained in the following 3 steps.
Figure 1Odds ratios for reprocessing covariates. AM20, Microbial growth with ≥20 colony-forming units/20 mL of any type of microorganism; ATP, adenosine triphosphate; OR, odds ratio; CI, credible interval.
First, a secondary analysis (Table 2, Fig. 2) assessing the intervention period effect per endoscope type showed that the effect was based on only ED34-i10T duodenoscopes, whereas no effect was seen in the other endoscope types. ED34-i10T duodenoscopes had during the intervention period a lower estimated probability of contamination with gut flora compared with the control period (control vs intervention period: mean, 39.0% [95% CI, 17.6%-63.6%] vs 9.1% [95% CI, 2%-21%]).
Table 2Distribution of the estimated probability of gut flora contamination
Gut flora
Control
Intervention
Difference
Duodenoscopes
Olympus TJF-160VR
15.4 (3.5-37.2)
8.8 (2.0-22.0)
–6.6 (–27.7 to 8.7)
Pentax ED34-i10T2 disposable elevator cap
15.6 (.2-60.0)
43.4 (18.4-72.1)
27.8 (–18.6 to 63.5)
Pentax ED34-i10T
39.0 (17.6-63.6)
9.1 (2.4-20.9)
–29.9 (-52.3 to –11.0)
Linear echoendoscopes
Pentax EG-3270UK
4.7 (.1-23.1)
10.2 (1.4-33.4)
5.5 (–10.4 to 26.5)
Pentax EG-3870UTK
4.8 (1.2-12.3)
4.2 (1.2-10.2)
–.06 (–7.7 to 5.3)
Estimated probabilities (in %) of gut flora contamination during the control and intervention periods with corresponding 95% credible intervals, under the assumption of reference values (old building, core team, study week 23, 39 procedures) for the other covariates. Pentax ED34-i10T includes duodenoscopes A, B, C, and D as shown in Figure 3.
Figure 2Distribution of the estimated probability of contamination by control period and intervention period as well as endoscope type. Other covariates were old endoscopy unit, core disinfection assistant team, study week 23, and 39 procedures. Pentax ED34-i10T includes duodenoscopes A, B, C, and D as shown in Figure 3. AM20, Microbial growth with ≥20 colony-forming units/20 mL of any type of microorganism; ATP, adenosine triphosphate.
Second, close observation of the 4 ED34-i10T duodenoscopes showed that duodenoscopes A and B had lower gut flora contamination rates in the intervention period: A, 69% (n = 29) versus 39% (n = 16), and B, 36% (n = 13) versus 10% (n = 2). The other 2 duodenoscopes had very few observations (C, 13% [n = 6] vs 14% [n = 1], and D, 20% [n = 4] vs 25% [n = 2]) and could thus contribute little to the results of the secondary analysis.
Third, it was observed that the control period gut flora rates of duodenoscopes A and B were predominantly caused by episodes of ongoing contamination, which ended before the start of the intervention period (Fig. 3). Both duodenoscopes had an episode with Enterobacter cloacae complex and Klebsiella pneumoniae, and duodenoscope A had another episode with Candida parapsilosis. The episodes were only detected by regular surveillance cultures after multiple positive blind study cultures, but the C parapsilosis episode was not detected at all. These episodes ended in November, and further study and surveillance cultures remained negative for gut flora in the control period. Because no gut flora was present at the start of the intervention period, this indicates that ATP testing did not terminate these episodes. Also in the intervention period, new episodes with gut flora emerged among 1 ED34-i10T duodenoscope and 3 ED34-i10T2 duodenoscopes. Duodenoscope A had a third episode with Stenotrophomonas maltophilia in its final month in the intervention period (Fig. 3), and 3 ED34-i10T2 duodenoscopes had up to 2-month-long episodes with Enterobacter aerogenes, E cloacae complex, S maltophilia, C parapsilosis, and yeasts. These new episodes during the intervention period indicate that ATP testing did not prevent ongoing gut flora contamination.
Figure 3Timeline of Pentax ED34-i10T duodenoscopes. Four Pentax ED34-i10T duodenoscopes (A, B, C, and D) were in use until week 40. Microbiologic surveillance was performed monthly; endoscopes contaminated with gut flora were quarantined until they were effectively decontaminated as shown by surveillance cultures. Results of surveillance cultures are delayed because of the 72-hour incubation period. Columns represents study cultures. Both researchers and clinicians were blinded to the result of study cultures. Circles represent surveillance cultures, which are only shown if positive for gut flora. Gray columns are negative for gut flora, whereas colored columns or circles are positive for gut flora. Pentax inspected endoscopes after ongoing positive surveillance cultures. This is shown as an inspection if no defects were detected and as repair if damage and/or wear required repairs and replacement of parts.
Sample sites that were ATP-positive after cleaning harbored gut flora after HLD in a selected number of cases. Of all endoscopes, the elevator and cap were the sites that were most often ATP-positive during the control (both sites ≥66%) and intervention (both sites ≥27%) periods (Supplementary Table 1, available online at www.giejournal.org). However, these sites had the lowest gut flora contamination rates (elevator, 2% [n = 16]; cap, <1% [n = 1]) (Supplementary Table 2, available online at www.giejournal.org). A similar pattern was seen in the channels of linear echoendoscopes. Although 38% tested ATP-positive in the control period and 16% in the intervention period, the gut flora contamination rates detected by channel flush and brush were lower (control period, 3%; intervention period, 7%). On the other hand, sample sites that did harbor gut flora were ATP-positive in a low number of cases. Of all sample sites, duodenoscope channels harbored the most gut flora (flush and brush combined: control period, 26%; intervention period, 32%), but the channels tested ATP-positive the least often in the control period (15%) and intervention period (5%). This was in particular the case for ED34-i10T2 duodenoscopes: 52% (n = 54) were contaminated with gut flora during the intervention period, but 3% (n = 3) tested ATP-positive. This contrast indicates a low correlation between a positive postcleaning ATP test and presence of gut flora in terminal cultures.
AM20 contamination
The main analysis also showed that the intervention period did not reduce AM20 contamination rates (odds ratio, 2.03; 95% CI, .77-5.85) (Fig. 1), which is consistent with the AM20 contamination rates of all DLEs (>34% in both periods) (Table 1). AM20 contamination did become more likely per each 50 procedures performed during the time that the study progressed (odds ratio, 1.01; 95% CI, 1.00-1.02). In particular, ED34-i10T (86%, n = 197) and ED34-i10T2 (49%, n = 60) duodenoscopes had consistently high AM20 rates (Supplementary Table 3, available online at www.giejournal.org). The secondary analysis (Table 2, Fig. 2), assessing the intervention period effect per endoscope type, showed slightly higher estimated probabilities for all endoscope types in the intervention period but not large enough to conclude a negative impact with certainty. Contamination rates in relation to ERCP and EUS specifics are presented in Supplementary Table 4 (available online at www.giejournal.org).
Recleaning
In the intervention period, DLEs that underwent extra cleaning because of a positive ATP test had lower gut flora contamination rates (Table 1). This was both the case for duodenoscopes (gut flora: 37% [n = 74] vs 15% [n = 8]) and linear echoendoscopes (gut flora: 12% [n = 14] vs 6% [n = 6]).
Discussion
In our prospective before-and-after study, introduction of postmanual cleaning ATP tests did not reduce the post-HLD gut flora contamination rate of DLEs and thus did not stop or prevent the use of endoscopes contaminated with gut flora. We found a lower odds on gut flora contamination during the intervention period (21% vs 16%). However, this was based on 2 duodenoscopes with episodes of ongoing contamination during the control period, which were ended by quarantining and repairs. Until detected by routine clinical surveillance cultures, these episodes could go unnoticed; both researchers and clinicians were blinded to results of study cultures. The results of this study suggest that the currently used ATP test (ie, 4 sample sites with a 200-RLU cutoff) is unsuitable to detect inadequately cleaned endoscopes and therefore should not be used as a cleaning quality control indicator. Furthermore, monthly surveillance cultures are inadequate to prevent the use of contaminated equipment. Improvement of the reliability of quality checks and microbiologic surveillance regimens is required to prevent the risk of microbial transmission by contaminated endoscopes. Eventually, this risk must be eliminated by a radical redesign of DLEs and reprocessing methods.
The current study confirms the results of a small clinical pilot and a simulated-use study, which both showed that postmanual cleaning ATP tests are not effective in preventing contamination of pathogenic bacteria in duodenoscopes.
Adenosine triphosphate bioluminescence for bacteriological surveillance and reprocessing strategies for minimizing risk of infection transmission by duodenoscopes.
Adenosine triphosphate bioluminescence for bacteriological surveillance and reprocessing strategies for minimizing risk of infection transmission by duodenoscopes.
which prevented drawing a final conclusion about the clinical merits of the ATP test. The current study, with a controlled and adequately powered design, showed that postcleaning ATP tests do not have a clinically relevant effect.
We found a discrepancy between an ATP-positive test result and the presence of gut flora. The elevator and cap of all DLEs as well as the channels of echoendoscopes had high ATP-positive rates, but only a small number harbored gut flora. On the contrary, ED34-i10T2 duodenoscopes were ATP-positive in only 3 cases. Although some studies did find a correlation between ATP and microbial load after manual cleaning,
The discrepancy can be explained by the fact that positive ATP results combined with cultures negative for gut flora can be the result of organic residue containing ATP, such as human secretions or cells, a high microbial load of non–gut flora, or noncultivable microorganisms. The 200-RLU cutoff is validated for the distal tip and flush,
Comparison of clinically relevant benchmarks and channel sampling methods used to assess manual cleaning compliance for flexible gastrointestinal endoscopes.
but for the experimental cap and elevator sites no validation data are known. ATP-negative results in combination with cultures positive for gut flora can be the result of a gut flora microbial load too low to raise the number of RLUs.
Another explanation can be that the ATP water test is not sensitive enough because the material is diluted by the flush water (40 mL), whereas cultures detect all viable CFUs in a channel flush as its filter is cultured. Detection is further increased by also sampling channels with a brush.
These results imply that the ATP test as used in this study cannot adequately detect gut flora. The lower ATP test positivity rate in the intervention period can be the result of revised reprocessing routines (ie, improved cleaning and endoscope handling) and the introduction of disposable caps for ED34-i10T duodenoscopes.
Recleaned DLEs had lower gut flora contamination rates, suggesting extra cleaning reduces organic debris. Because manual cleaning is error-prone,
Implementation of remote video auditing with feedback and compliance for manual-cleaning protocols of endoscopic retrograde cholangiopancreatography endoscopes.
a quality control indicator that appropriately detects inadequately cleaned endoscopes would be a benefit. Current evidence does not support the ATP test for this use: Improvement of ATP test rates while gut flora rates remain high is a false-negative test result providing an incorrect and false sense of security.
Contamination rates of linear echoendoscopes in this study were in line with previous studies,
whereas duodenoscope rates were remarkably higher. These high rates can be the result of the study design, endoscope-related issues, and/or sampling and culture methods. Large-scale studies with far lower rates conducted daily or postprocedure surveillance in an open study design
allowed immediate quarantine of contaminated endoscopes, which prevented further use. For most hospitals daily surveillance is too labor intense and expensive.
High contamination rates in studies blinded to study culture outcomes are perhaps more representative of their clinical practice. High rates were also found in cross-sectional studies,
Independent root-cause analysis of contributing factors, including dismantling of 2 duodenoscopes, to investigate an outbreak of multidrug-resistant Klebsiella pneumoniae.
The high rates in this study were mainly based on contamination episodes of a select number of Pentax-type duodenoscopes. Recurrent episodes of gut flora and ongoing contamination with waterborne and/or skin flora in both types suggest the presence of biofilms in endoscope channels, including new duodenoscopes. Once present, a biofilm can be the cause of failure of reprocessing.
Independent root-cause analysis of contributing factors, including dismantling of 2 duodenoscopes, to investigate an outbreak of multidrug-resistant Klebsiella pneumoniae.
In our study in duodenoscope A, the first episode ended only after the third servicing, whereas in duodenoscope B the episode continued despite servicing. Close cooperation and taking joint responsibility by both end users and endoscope manufacturers for reprocessing, strict surveillance, and servicing are important in guarding endoscope safety.
This study showed that monthly surveillance was inadequate for the timely detection of contamination. Until detected by surveillance cultures, episodes that lasts multiple weeks continue to expose patients to contaminated equipment. One episode of C parapsilosis was “missed” (ie, not present in any surveillance culture). This is in line with the fact that during contamination episodes not all consecutive study cultures are positive for the same bacteria species. Therefore, high-frequency daily or weekly surveillance should be considered to detect ongoing contamination patterns.
To the best of our knowledge, this is the first controlled study with blinded study cultures required to investigate postcleaning ATP tests. The current study also has some limitations. Generalizability of the results is limited by multiple factors including the single-center design and susceptibility of distinct endoscopes to contamination. The intervention period had a longer duration than the control period because of a lower inclusion rate. This was because depending on the number of daily procedures and available endoscopes, not all endoscopes could undergo the longer intervention period ATP test cycle. Major reprocessing-affecting events that occurred during the study were accounted for by including these factors in the statistical analysis model.
To conclude, this before-and-after intervention study shows that postmanual cleaning ATP tests as used in this study do not reduce the number of contaminated DLEs after HLD. To prevent the use of contaminated equipment, reliable control measures are required to assess whether reprocessing of reusable DLEs was adequate. Until the risk of contamination is eliminated by sterilization of DLEs or single-use endoscopes, strict and frequent microbiologic surveillance is indicated.
Acknowledgment
We thank the reprocessing staff, sampling staff, medical devices experts, infection control professionals, medical microbiologists, and gastroenterologists at the Erasmus MC for their participation and efforts in this study.
Appendix
Supplementary Figure 1Flowchart. Adenosine triphosphate (ATP) negative refers to test results of all sites that were ≤200 relative light units (RLUs), whereas ATP positive refers to ≥1 test site result that was ≥201 RLUs.
Supplementary Figure 2Timeline of inclusion and outcome rates per endoscope type. Each line represents 1 endoscope, and each dot marks a measurement. Vertical dotted lines represent the divide between the control and intervention periods. Blue dots represent a negative outcome. Red dots in the first column represent endoscopes contaminated with gut flora, red dots in the second column represent endoscopes contaminated with AM20, and red dots in the third column represent endoscopes with a positive first ATP test. AM20, Microbial growth with ≥20 colony-forming units/20 mL of any type of microorganism; ATP, adenosine triphosphate.
Twenty-seven weeks after the start of the intervention period, the endoscopy department changed to single-use protection caps for the Pentax ED34-i10T. Therefore, the number is lower than the total number of endoscopes.
Twenty-seven weeks after the start of the intervention period, the endoscopy department changed to single-use protection caps for the Pentax ED34-i10T. Therefore, the number is lower than the total number of endoscopes.
Twenty-seven weeks after the start of the intervention period, the endoscopy department changed to single-use protection caps for the Pentax ED34-i10T. Therefore, the number is lower than the total number of endoscopes.
Pentax ED34-i10T2 with disposable elevator cap
Control
17
7 (41)
3 (18)
2 (12)
6 (35)
—
Intervention first ATP test
106
3 (3)
1 (1)
2 (2)
2 (2)
—
Intervention second ATP test
3
1 (33)
2 (66)
0
2 (66)
—
Intervention third ATP test
1
0
0
0
0
—
Olympus TJF-160VR
Control
54
44 (81)
29 (54)
10 (19)
38 (70)
32 (59)
Intervention first ATP test
64
24 (38)
11 (17)
8 (13)
20 (31)
19/61 (31)
Intervention second ATP test
24
8 (33)
3 (13)
2 (8)
6 (25)
7/22 (32)
Intervention third ATP test
8
5 (63)
2 (25)
0
4 (50)
4/8 (50)
Linear echoendoscopes
Pentax EG-3870UTK
Control
145
125 (86)
106 (73)
56 (39)
111 (77)
—
Intervention first ATP test
187
90 (48)
47 (25)
27 (14)
69 (37)
—
Intervention second ATP test
88
35 (40)
18 (20)
5 (6)
23 (26)
—
Intervention third ATP test
33
15 (45)
5 (15)
4 (12)
14 (42)
—
Pentax EG-3270UK
Control
57
43 (75)
26 (46)
20 (35)
38 (67)
—
Intervention first ATP test
38
18 (47)
12 (32)
9 (24)
14 (37)
—
Intervention second ATP test
18
4 (22)
3 (17)
1 (6)
2 (11)
—
Intervention third ATP test
4
3 (75)
2 (50)
0
2 (50)
—
Values are n or n/N (%) unless otherwise defined.
ATP, Adenosine triphosphate; —, not applicable.
∗ Twenty-seven weeks after the start of the intervention period, the endoscopy department changed to single-use protection caps for the Pentax ED34-i10T. Therefore, the number is lower than the total number of endoscopes.
Twenty-seven after the start of the intervention period, single-use protection caps were introduced, resulting in a lower number lower of cap samples.
Pentax ED34-i10T2 with disposable elevator cap
Control
17
1 (6)
1 (6)
0
0
—
Intervention first cleaning
103
52 (50)
29 (28)
39 (38)
1 (1)
—
Intervention second cleaning
2
1 (50)
0
1 (50)
0
—
Intervention third cleaning
1
1
1
1
1
—
Olympus TJF-160VR
Control
56
7 (13)
2 (4)
5 (9)
0
0
Intervention first cleaning
40
4 (10)
1 (3)
1 (3)
2 (5)
0
Intervention second cleaning
16
1 (6)
0
1 (6)
0
0
Intervention third cleaning
8
2 (25)
0
2 (25)
0
0
Linear echoendoscopes
Pentax EG-3870UTK
Control
147
5 (3)
4 (3)
1 (1)
1 (1)
—
Intervention first cleaning
97
12 (12)
5 (5)
4 (4)
5 (5)
—
Intervention second cleaning
55
2 (4)
1 (2)
2 (4)
0
—
Intervention third cleaning
35
1 (3)
0
1 (3)
0
—
Pentax EG-3270UK
Control
58
1 (2)
1 (2)
0
0
—
Intervention first cleaning
20
1 (5)
0
1 (5)
0
—
Intervention second cleaning
14
3 (21)
2 (14)
0
2 (14)
—
Intervention third cleaning
4
0
0
0
0
—
Values in parentheses are percents.
—, Not applicable.
∗ Not all duodenoscope and linear echoendoscope types have (reusable) protection caps.
† Twenty-seven after the start of the intervention period, single-use protection caps were introduced, resulting in a lower number lower of cap samples.
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DISCLOSURE: The following authors disclosed financial relationships: M. C. Vos: Researchgrantfrom 3M, Pentax Medical, and IMS Innovations; unrestricted gift from Lely Company. M. J. Bruno: Consultant for 3M, Boston Scientific, and Cook Medical; researchgrantfrom 3M, Boston Scientific, Cook Medical, and Pentax Medical; lecturer for Boston Scientific and Cook Medical. All other authors disclosed no financial relationships. Researchsupportfor this study was provided by an unrestrictedgrantfrom 3M Health Care.
DIVERSITY, EQUITY, AND INCLUSION: The author list of this paper includes contributors from the location where the research was conducted who participated in the data collection, design, analysis, and/or interpretation of the work.
If you would like to chat with an author of this article, you may contact Dr Bruno at [email protected]
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