Residual moisture and waterborne pathogens inside flexible endoscopes: Evidence from a multisite study of endoscope drying effectiveness

Published:March 30, 2018DOI:


      • Moisture may foster microbial growth and biofilm development in endoscopes.
      • Retained moisture was detected in 49% of endoscopes.
      • Microbial growth was found in samples from 71% of endoscopes.
      • Retained fluid was associated with higher ATP levels and microbial growth.
      • Improvements in reprocessing and drying methods are needed to ensure patient safety.


      Endoscopy-associated infection transmission is frequently linked to inadequate reprocessing. Residual organic material and moisture may foster biofilm development inside endoscopes. This study evaluated the effectiveness of endoscope drying and storage methods and assessed associations between retained moisture and contamination.


      Endoscope reprocessing, drying, and storage practices were assessed at 3 hospitals. Researchers performed visual examinations and tests to detect fluid and contamination on patient-ready endoscopes.


      Fluid was detected in 22 of 45 (49%) endoscopes. Prevalence of moisture varied significantly by site (5%; 83%; 85%; P < .001). High adenosine triphosphate levels were found in 22% of endoscopes, and microbial growth was detected in 71% of endoscopes. Stenotrophomonas maltophilia, Citrobacter freundii, and Lecanicillium lecanii/Verticillium dahliae were found. Retained fluid was associated with significantly higher adenosine triphosphate levels (P < .01). Reprocessing and drying practices conformed with guidelines at 1 site and were substandard at 2 sites. Damaged endoscopes were in use at all sites.


      Inadequate reprocessing and insufficient drying contributed to retained fluid and contamination found during this multisite study. More effective methods of endoscope reprocessing, drying, and maintenance are needed to prevent the retention of fluid, organic material, and bioburden that could cause patient illness or injury.

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        • Rutala W.A.
        • Weber D.J.
        Gastrointestinal endoscopes: a need to shift from disinfection to sterilization?.
        JAMA. 2014; 312: 1405-1406
        • ECRI Institute
        Executive Brief: Top 10 Health Technology Hazards for 2018.
        ECRI Institute, Plymouth Meeting, PA2017: 5
        • Ofstead C.L.
        • Dirlam Langlay A.M.
        • Mueller N.J.
        • Tosh P.K.
        • Wetzler H.P.
        Re-evaluating endoscopy-associated infection risk estimates and their implications.
        Am J Infect Control. 2013; 41: 734-736
        • Kovaleva J.
        • Peters F.T.
        • van der Mei H.C.
        • Degener J.E.
        Transmission of infection by flexible gastrointestinal endoscopy and bronchoscopy.
        Clin Microbiol Rev. 2013; 26: 231-254
        • Food and Drug Administration
        Infections associated with reprocessed flexible bronchoscopes: FDA safety communication. FDA Safety Communication.
        (Available from)
        • Rubin Z.A.
        • Murthy R.K.
        Outbreaks associated with duodenoscopes: new challenges and controversies.
        Curr Opin Infect Dis. 2016; 29: 407-414
        • Ross A.S.
        • Baliga C.
        • Verma P.
        • Duchin J.
        • Gluck M.
        A quarantine process for the resolution of duodenoscope-associated transmission of multidrug-resistant Escherichia coli.
        Gastrointest Endosc. 2015; 82: 477-483
        • Wendorf K.A.
        • Kay M.
        • Baliga C.
        • Weissman S.G.
        • Gluck M.
        • Verma P.
        • et al.
        Endoscopic retrograde cholangiopancreatography-associated AmpC Escherichia coli outbreak.
        Infect Control Hosp Epidemiol. 2015; 36: 634-642
        • Epstein L.
        • Hunter J.C.
        • Arwady M.A.
        • Tsai V.
        • Stein L.
        • Gribogiannis M.
        • et al.
        New Delhi metallo-beta-lactamase-producing carbapenem-resistant Escherichia coli associated with exposure to duodenoscopes.
        JAMA. 2014; 312: 1447-1455
        • Bajolet O.
        • Ciocan D.
        • Vallet C.
        • de Champs C.
        • Vernet-Garnier V.
        • Guillard T.
        • et al.
        Gastroscopy-associated transmission of extended-spectrum beta-lactamase-producing Pseudomonas aeruginosa.
        J Hosp Infect. 2013; 83: 341-343
        • Food and Drug Administration
        MAUDE Adverse Event Report: Olympus Medical Systems Corporation Olympus Evis Exera II GI videoscope gastrointestinal videoscope.
        (MDR Report Key 2835386; Available from)
        • Wendelboe A.M.
        • Baumbach J.
        • Blossom D.B.
        • Frank P.
        • Srinivasan A.
        • Sewell C.M.
        Outbreak of cystoscopy related infections with Pseudomonas aeruginosa: New Mexico, 2007.
        J Urol. 2008; 180 (discussion 592): 588-592
        • Jimeno A.
        • Alcalde M.M.
        • Ortiz M.
        • Rodriguez A.
        • Alcaraz B.
        • Vera F.
        Outbreak of urinary tract infections by Salmonella spp. after cystoscopic manipulation.
        Actas Urol Esp. 2016; 40: 646-649
        • English L.T.
        • Burwell L.
        • Terashita D.
        Outpatient medical procedures and patient safety: Who's minding the store?.
        in: Acute Communicable Disease Control Program Special Studies Report. Los Angeles County Department of Public Health, Los Angeles, CA2007: 19-24 (Available from)
        • Chang C.L.
        • Su L.H.
        • Lu C.M.
        • Tai F.T.
        • Huang Y.C.
        • Chang K.K.
        Outbreak of ertapenem-resistant Enterobacter cloacae urinary tract infections due to a contaminated ureteroscope.
        J Hosp Infect. 2013; 85: 118-124
        • Parton L.
        • Schomer K.
        Urinary tract infection outbreak: Investigation, interventions, and outcomes.
        Association of periOperative Registered Nurses Global Surgical Conference & Expo, 2013
        • Dickson A.
        Enterobacter cloacae found in an endobronchial ultrasound scope (EBUS): Now what do we do?.
        Association for Professionals in Infection Control and Epidemiology Annual Conference, Portland, OR2017
        • Jørgensen S.B.
        • Bojer M.S.
        • Boll E.J.
        • Martin Y.
        • Helmersen K.
        • Skogstad M.
        • et al.
        Heat-resistant, extended-spectrum β-lactamase-producing Klebsiella pneumoniae in endoscope-mediated outbreak.
        J Hosp Infect. 2016; 93: 57-62
        • Guy M.
        • Vanhems P.
        • Dananche C.
        • Perraud M.
        • Regard A.
        • Hulin M.
        • et al.
        Outbreak of pulmonary Pseudomonas aeruginosa and Stenotrophomonas maltophilia infections related to contaminated bronchoscope suction valves, Lyon, France, 2014.
        Euro Surveill. 2016; 21
        • Zweigner J.
        • Gastmeier P.
        • Kola A.
        • Klefisch F.R.
        • Schweizer C.
        • Hummel M.
        A carbapenem-resistant Klebsiella pneumoniae outbreak following bronchoscopy.
        Am J Infect Control. 2014; 42: 936-937
        • Machida H.
        • Seki M.
        • Yoshioka N.
        • Yabuno K.
        • Miyawaki K.
        • Yoshida H.
        • et al.
        Correlation between outbreaks of multidrug-resistant Pseudomonas aeruginosa infection and use of bronchoscopes suggested by epidemiological analysis.
        Biol Pharm Bull. 2014; 37: 26-30
        • England D.
        • Houseman J.
        • Horn L.
        • Mascotti K.
        • Kline S.
        Documented transmission of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae from patient to gastroscope.
        Infect Control Hosp Epidemiol. 2016; 37: 493-494
        • Visrodia K.H.
        • Ofstead C.L.
        • Yellin H.L.
        • Wetzler H.P.
        • Tosh P.K.
        • Baron T.H.
        The use of rapid indicators for the detection of organic residues on clinically used gastrointestinal endoscopes with and without visually apparent debris.
        Infect Control Hosp Epidemiol. 2014; 35: 987-994
        • Brandabur J.J.
        A randomized trial of single versus double high-level disinfection (HLD) of duodenoscopes and linear echoendoscopes using standard automated reprocessing.
        Digestive Disease Week, Chicago, IL2017
        • Snyder G.M.
        • Wright S.B.
        • Smithey A.
        • Mizrahi M.
        • Sheppard M.
        • Hirsch E.B.
        • et al.
        Randomized comparison of 3 high-level disinfection and sterilization procedures for duodenoscopes.
        Gastroenterology. 2017; 153: 1018-1025
        • Ofstead C.L.
        • Wetzler H.P.
        • Heymann O.L.
        • Johnson E.A.
        • Eiland J.E.
        • Shaw M.J.
        Longitudinal assessment of reprocessing effectiveness for colonoscopes and gastroscopes: Results of visual inspections, biochemical markers, and microbial cultures.
        Am J Infect Control. 2017; 45: e26-e33
        • Ofstead C.L.
        • Wetzler H.P.
        • Eiland J.E.
        • Heymann O.L.
        • Held S.B.
        • Shaw M.J.
        Assessing residual contamination and damage inside flexible endoscopes over time.
        Am J Infect Control. 2016; 44: 1675-1677
        • Ofstead C.L.
        • Wetzler H.P.
        • Doyle E.M.
        • Rocco C.K.
        • Visrodia K.H.
        • Baron T.H.
        • et al.
        Persistent contamination on colonoscopes and gastroscopes detected by biologic cultures and rapid indicators despite reprocessing performed in accordance with guidelines.
        Am J Infect Control. 2015; 43: 794-801
        • Ofstead C.L.
        • Wetzler H.P.
        • Johnson E.A.
        • Heymann O.L.
        • Maust T.J.
        • Shaw M.J.
        Simethicone residue remains inside gastrointestinal endoscopes despite reprocessing.
        Am J Infect Control. 2016; 44: 1237-1240
        • Thaker A.M.
        • Kim S.
        • Sedarat A.
        • Watson R.R.
        • Muthusamy R.
        Inspection of endoscope instrument channels after reprocessing using a prototype video camera: A pilot study.
        Digestive Disease Week, Chicago, IL2017
        • Kovaleva J.
        Endoscope drying and its pitfalls.
        J Hosp Infect. 2017; 97: 319-328
        • Saliou P.
        • Le Bars H.
        • Payan C.
        • Narbonne V.
        • Cholet F
        • Jézéquel J.
        • et al.
        Measures to improve microbial quality surveillance of gastrointestinal endoscopes.
        Endoscopy. 2016; 48: 704
        • Stigt J.A.
        • Wolfhagen M.J.
        • Smulders P.
        • Lammers V.
        The identification of Stenotrophomonas maltophilia contamination in ultrasound endoscopes and reproduction of decontamination failure by deliberate soiling tests.
        Respiration. 2015; 89: 565-571
        • Coton T.
        • Sbai W.
        • Beaussac M.
        • Luciano L.
        • Gay G.
        • Garnotel E.
        New flexible endoscopes: Surprising bacterial colonization post-disinfection.
        Clin Res Hepatol Gastroenterol. 2017; 41: e63-e64
        • Ofstead C.L.
        • Doyle E.M.
        • Eiland J.E.
        • Amelang M.R.
        • Wetzler H.P.
        • England D.M.
        • et al.
        Practical toolkit for monitoring endoscope reprocessing effectiveness: Identification of viable bacteria on gastroscopes, colonoscopes, and bronchoscopes.
        Am J Infect Control. 2016; 44: 815-819
        • Visrodia K.
        • Hanada Y.
        • Pennington K.M.
        • Tosh P.K.
        • Topazian M.D.
        • Petersen B.T.
        Duodenoscope reprocessing surveillance with adenosine triphosphate testing and terminal cultures: A clinical pilot study.
        Gastrointest Endosc. 2017; 86: 180-186
        • Association of Perioperative Registered Nurses
        Guideline for processing flexible endoscopes.
        in: Sterilization and disinfection. AORN, Denver, CO2016: 675-758
        • Society of Gastroenterology Nurses Association
        Standards of infection prevention in reprocessing flexible gastrointestinal endoscopes.
        SGNA, Chicago, IL2015: 1-31
        • Association for the Advancement of Medical Instrumentation
        • American National Standards Institute
        ANSI/AAMI ST91: 2015, Flexible and semi-rigid endoscope processing in health care facilities.
        AAMI, Arlington, VA2015: 1-70
        • Alfa M.J.
        • Sitter D.L.
        In-hospital evaluation of contamination of duodenoscopes: a quantitative assessment of the effect of drying.
        J Hosp Infect. 1991; 19: 89-98
        • Ribeiro M.M.
        • de Oliveira A.C.
        • Ribeiro S.M.
        • Watanabe E.
        • de Resende Stoianoff M.A.
        • Ferreira J.A.
        Effectiveness of flexible gastrointestinal endoscope reprocessing.
        Infect Control Hosp Epidemiol. 2013; 34: 309-312
        • Alfa M.J.
        • Fatima I.
        • Olson N.
        Validation of adenosine triphosphate to audit manual cleaning of flexible endoscope channels.
        Am J Infect Control. 2013; 41: 245-248
        • Alfa M.J.
        • Ribeiro M.M.
        • da Costa Luciano C.
        • Franca R.
        • Olson N.
        • DeGagne P.
        • et al.
        A novel polytetrafluoroethylene-channel model, which simulates low levels of culturable bacteria in buildup biofilm after repeated endoscope reprocessing.
        Gastrointest Endosc. 2017; 86: 442-451
        • Alfa M.J.
        • Olson N.
        • Murray B.L.
        Comparison of clinically relevant benchmarks and channel sampling methods used to assess manual cleaning compliance for flexible gastrointestinal endoscopes.
        Am J Infect Control. 2014; 42: e1-e5
        • Seidelman J.
        • Lewis S.S.
        • Keating A.
        • Chen L.F.
        Investigating a Mycobacterium avium complex pseudo-outbreak associated with outpatient bronchoscopy clinic: Lessons for reprocessing.
        Infectious Diseases Week, New Orleans, LA2016
        • Catalone B.J.
        Simethicone. Letter to health care practitioner.
        Olympus America, Inc, Center Valley, PA2009
        • Pentax Medical Company
        Instruction for use: Pentax Video GI Scopes 90i Series 90K Series.
        Hoya Corporation, Tokyo, Japan2014
        • van Stiphout S.H.
        • Laros I.F.
        • van Wezel R.A.
        • Gilissen L.P.
        Crystallization in the waterjet channel in colonoscopes due to simethicone.
        Endoscopy. 2016; 48: e394-e395
        • Benmassaoud A.
        • Parent J.
        CAG position statement: The impact of simethicone on endoscope reprocessing.
        Canadian Association of Gastroenterology, Oakville, ON, Canada2017: 1-4
        • Verfaillie C.J.
        • Bruno M.J.
        • Voor in ‘t Holt A.F.
        • Buijs J.G.
        • Poley J.W.
        • Loeve A.J.
        • et al.
        Withdrawal of a novel-design duodenoscope ends outbreak of a VIM-2-producing Pseudomonas aeruginosa.
        Endoscopy. 2015; 47: 493-502
        • Beilenhoff U.
        • Neumann C.S.
        • Rey J.F.
        • Biering H.
        • Blum R.
        • Cimbro M.
        • et al.
        ESGE-ESGENA guideline: cleaning and disinfection in gastrointestinal endoscopy.
        Endoscopy. 2008; 40: 939-957
        • Taylor A.
        • Jones D.
        • Everts R.
        • Cowen A.
        • Wardle E.
        Infection control in endoscopy.
        3rd ed. Gastroenterological Society of Australia and Gastroenterological Nurses College of Australia, Australia2011: 1-66
        • Costa D.M.
        • Lopes L.K.O.
        • Hu H.
        • Tipple A.F.V.
        • Vickery K.
        Alcohol fixation of bacteria to surgical instruments increases cleaning difficulty and may contribute to sterilization inefficacy.
        Am J Infect Control. 2017; 45: e81-e86
        • Thomas P.
        Long-term survival of Bacillus spores in alcohol and identification of 90% ethanol as relatively more spori/bactericidal.
        Curr Microbiol. 2012; 64: 130-139
        • Pineau L.
        • Villard E.
        • Duc D.L.
        • Marchetti B.
        Endoscope drying/storage cabinet: interest and efficacy.
        J Hosp Infect. 2008; 68: 59-65
        • Grandval P.
        • Hautefeuille G.
        • Marchetti B.
        • Pineau L.
        • Laugier R.
        Evaluation of a storage cabinet for heat-sensitive endoscopes in a clinical setting.
        J Hosp Infect. 2013; 84: 71-76
        • Saliou P.
        • Cholet F.
        • Jezequel J.
        • Robaszkiewicz M.
        • Le Bars H.
        • Baron R.
        The use of channel-purge storage for gastrointestinal endoscopes reduces microbial contamination.
        Infect Control Hosp Epidemiol. 2015; 36: 1100-1102
        • Brandabur J.J.
        • Leggett J.E.
        • Wang L.
        • Bartles R.L.
        • Baxter L.
        • Diaz G.A.
        • et al.
        Surveillance of guideline practices for duodenoscope and linear echoendoscope reprocessing in a large health system.
        Gastrointest Endosc. 2016; 84: 392-399
        • Ofstead C.L.
        • Heymann O.L.
        • Quick M.R.
        • Johnson E.A.
        • Eiland J.E.
        • Wetzler H.P.
        The effectiveness of sterilization for flexible ureteroscopes: a real-world study.
        Am J Infect Control. 2017; 45: 888-895
        • Fushimi R.
        • Takashina M.
        • Yoshikawa H.
        • Kobayashi H.
        • Okubo T.
        • Nakata S.
        • et al.
        Comparison of adenosine triphosphate, microbiological load, and residual protein as indicators for assessing the cleanliness of flexible gastrointestinal endoscopes.
        Am J Infect Control. 2013; 41: 161-164
        • Rex D.K.
        • Sieber M.
        • Lehman G.A.
        • et al.
        A double-reprocessing high-level disinfection protocol does not eliminate positive cultures from the elevators of duodenoscopes.
        Endoscopy. 2017; (Dec 13; Epub ahead of print)
        • Association for the Advancement of Medical Instrumentation
        Strong evidence for sterilization of endoscopes presented at stakeholder meeting. AAMI Articles and Press Releases.
        (September 13)
        Date: 2017
        Date accessed: September 21, 2017
        • Storms L.
        Urgent medical device removal action: Olympus URF-P6/P6R uretero-reno fiberscope. Letter to health care professional.
        Olympus America, Inc, Center Valley, PA2018
        • Hamasuna R.
        • Takahashi S.
        • Yamamoto S.
        • Arakawa S.
        • Yanaijara H.
        • Ishikawa S.
        • et al.
        Guideline for the prevention of health care-associated infection in urological practice in Japan.
        Int J Urol. 2011; 18: 495-502