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 21 March 2018

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Endoscopy Practice and Safety

Editor: Peter B. Cotton

Infection control in endoscopy: Commentary

A. T. R. Axon

Top of page Synopsis  Next section

This chapter on infection control in endoscopy by Alistair Cowen and Dianne Jones is a comprehensive, thoughtful and well-written contribution from a group that has had longstanding interest and expertise in this area.

Top of page Most endoscopists are not interested  Previous section Next section

There is an extensive literature about the problems of disinfection of endoscopy equipment, and a plethora of guidelines advising how to minimize the risk of cross-infection. However, it must be admitted that endoscopists usually try to avoid reading or thinking about, or being involved with disinfection matters unless they are part of a working group set up to establish regulations, or they wish to write up an interesting case of cross-infection, or are involved in litigation as a result of the failure of procedures in their own department. The responsibility for preventing cross-infection has therefore been devolved largely to the nursing staff. Endoscopists can add to the problem by placing heavy demands on their nursing staff by pressing for a fast turn-round of equipment in order to complete their lists. This lack of empathy with endoscopic disinfection is understandable but problematic. As exhortation has not changed attitudes, consideration should be given to other means of ensuring that appropriate safety standards are maintained.

Top of page Is the problem declining?  Previous section Next section

Dr Cowen's chapter points out that assessments of patient-to-patient transmission based on retrospective analyses are almost certainly underestimates of the risk. In the 1980s there were a large number of case reports describing single episodes of cross-infection, and indeed some epidemics. Although many fewer are now reported, this does not necessarily imply that their number has declined. Whereas the original papers drew attention to what was then a new risk, editors today are unlikely to accept 'me too' case reports of Pseudomonas septicemia following ERCP, or cases of salmonella transmission.

Top of page Newly recognized infections  Previous section Next section

Interest has focused on the transmission of newer organisms such as hepatitis C. Although the majority of reports have been attributed to inadequate instrument reprocessing or poor intravenous sedation technique, some cases of infection do appear to have been transmitted by endoscopy in spite of reasonable precautions having been taken. Furthermore some viruses produce an initial subclinical infection (which may still lead to a carrier state or chronic disease), or there may be a significant incubation period in other cases. Under these circumstances post-endoscopy infection will be missed and therefore under-reported. This is particularly relevant when considering the statement that no case of HIV infection or variant CJD has been shown to have been transmitted endoscopically. That does not mean that infection has never been transmitted. A number of more recent reports of H. pylori transmission show that transmission of vegetative organisms still occurs. The observation that, in most of these instances, the disinfection procedure was improperly performed is no excuse. It merely draws attention to the fact that a number of endoscopy units do not reprocess their equipment properly according to official guidelines.

Top of page Compliance with guidelines  Previous section Next section

The chapter draws attention to studies that confirm the lack of compliance with cleaning and disinfection protocols, with more than 50% of units not following the guidelines. It also states that there is evidence of a substantial improvement in recent years, quoting two papers from the United States. In one of these, questionnaires were mailed to 730 randomly selected members of the ASGE [1], and appropriate disinfection methodology was used by 90.7% of respondents. There are three comments that should be made. Firstly, according to this survey, almost 10% of the units were using inadequate techniques. Secondly the data published was based on statements made by individuals, and the endoscopy process in the units was not independently inspected by the researchers. Thirdly the response rate to the questionnaire was a mere 40.3%, which could indicate significant selection bias.

Top of page What can be done to remedy this sorry state of affairs?  Previous section Next section

As was intimated earlier, the responsibility for ensuring adequate disinfection is largely delegated to nursing staff. Nurses in charge of endoscopy, particularly in smaller units, may be relatively inexperienced, or may not have been given the status or administrative support required for them to take a hard line with medical staff vis-à-vis the turn-round time of equipment.

Infection control staff  Previous section Next section

The responsibility for ensuring that endoscopy disinfection is adequate should be entrusted to a senior hospital employee with a background in hospital cross-infection. Endoscopists generally lack the interest (and even knowledge!) to be suitable applicants for the job. In the UK one individual (usually someone with knowledge of microbiology) is designated as being responsible for policing the cross-infection policy of the hospital. This probably pertains in other countries as well. It might be appropriate for this person to be legally responsible for ensuring that endoscope disinfection is performed properly. If so, a suitable job description might include the requirement for ensuring that adequate training is given to endoscopists and endoscopy assistants, that suitable equipment is available, that the day-to-day activities are overseen by a competent member of the nursing staff, and, most importantly, that regular audit of disinfection is performed. This approach would enable a quality assurance system to be introduced.

Microbiological surveillance  Previous section Next section

In our unit, each channel of every duodenoscope is swabbed weekly for microbiological culture, as are the endoscope reprocessors. However, when starting to write this article, I discovered that the gastroscopes and colonoscopes are not put through this rigorous check because the risks of infection from Pseudomonas in these procedures is small. Swabbing of all equipment at regular intervals would provide a check on the adequacy of the disinfection process. As most viruses are more easily eliminated by high-level disinfection than vegetative organisms, failure to grow contaminants would imply by proxy that the disinfection process is working adequately for most organisms.

British practice  Previous section Next section

We recently circulated a questionnaire to members of the British Society of Gastroenterology in order to ascertain whether this kind of audit was being undertaken in the UK [2]. We found that only 25% of 200 selected endoscopy units were routinely sampling their endoscopes and only 37% their reprocessors. Over the years that we have been auditing our disinfection procedures, apart from episodes of Pseudomonas contamination which have required attention periodically, we have identified mycobacteria in the hospital water supply resistant to glutaraldehyde. As a result we have had to change from glutaraldehyde to acidic electrolysed water, which provides high-level disinfection without the danger of staff toxicity or environmental pollution, and has the added advantage of providing inexpensive sterile rinsing water. The drawback to this system is that it causes deterioration of the outer surface of the endoscope insertion tube in certain makes of endoscope.

Top of page The role of industry  Previous section Next section

Manufacturers of endoscopes, reprocessors and disinfectants have important roles to play in improving disinfection technology. It would be desirable for all endoscope channels to be accessible for brushing. There is, as is often stated, no substitute for thorough mechanical cleaning. This cannot be undertaken unless the channel can be accessed with a brush. Non-toxic, effective, inexpensive disinfectants must be developed together with the instrument manufacturers to ensure that our endoscopes and equipment as well as our staff and patients are safe.

Top of page Manual cleaning is key  Previous section Next section

Every article on endoscope disinfection, including Dr Cowen's, emphasizes repeatedly that the most important step in endoscope disinfection is thorough manual cleaning. Is it not time to concentrate our efforts to ensure that this takes place?

Top of page References  Previous section

1 Cheung, RJ, Ortiz, D & DiMarino, AJ Jr. GI endoscopic reprocessing practices in the United States. Gastrointest Endosc 1999; 50: 362–8. PubMed

2 Rembacken, B, Butler, A & Axon, A. What is happening in the British endoscopy units? Endoscopy 2000; 32 (Suppl. 1): E65.

Copyright © Blackwell Publishing, 2003

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  A (very) brief history of endoscopy
  Professionalism and quality
Unit design
  Space planning
   Daily room volumes
   Procedure room size
   Preparation and recovery ratios
   Separate entrances
   Common space problems
  Physical infrastructure
  Intake and recovery areas
   Intake areas
   Managing clothes and valuables
   Recovery facilities
  Procedure room reprocessing and storage
   Standard procedure rooms
   Scope reprocessing and storage
   Patient flow issues
   Complex procedure rooms
   Storage of supplies and medications
   Travel carts for emergencies
Unit management
  Major areas of responsibility
  Staffing design
   Staffing emergencies
  Procedure schedules
   Relative time requirements
   Barriers to efficiency
   How many endoscopes?
   Endoscope repair costs
  Endoscope reprocessing
  Coding and billing
Outstanding issues and future trends
  Capsule endoscopy
  Colon screening technologies
  Endoscopy by non-specialists
  Growth of advanced endoscopy
  Moderate sedation
  Deep sedation/analgesia
Advances in monitoring during sedation
  Standard pulse oximetry
  CO2 monitoring
   Transcutaneous CO2 monitoring
  BIS monitoring
Topical anesthetics: are they worth the effort?
Titration vs. bolus administration of sedation and analgesia
  Problems with propofol
  Specific training for use of propofol
  Contraindications of propofol
  Clinical trials of propofol
   Propofol or midazolam?
   Upper endoscopy
   Upper endoscopy and colonoscopy
   Propofol with or without midazolam
   Patient-controlled administration of propofol
   Nurse-administered propofol
   Gastroenterologist-administered propofol
Outstanding issues and future trends
Gastrointestinal endoscopes
  Endoscope design
   Control section
   Insertion tube
   Connector section
   Light source/processors
  Endoscope equipment compatibility
  Endoscope categories
   Esophagogastroduodenoscope (gastroscope)
   Wireless capsule endoscopy
Gastrointestinal endoscopic accessories
  Tissue sampling
   Biopsy forceps
   Single-bite cold-biopsy forceps
   Biopsy cup jaws
   Multi-bite forceps
   Other specialty forceps
   Monopolar hot biopsy forceps
   Reusable vs. disposable biopsy
   Cytology brushes
   Needle aspiration
  Polypectomy snares
  Retrieval devices
  Injection devices
   Injection needles
   Spray catheters
   ERCP catheters
  Hemostatic and ablation devices
   Contact and non-contact thermal devices
   Heater probe
   Laser fibers
   Argon plasma beam coagulator
   Mechanical hemostatic devices
   Band ligation
   Metallic clip application via flexible endoscopes
   Marking with clips
   Detachable loops
  Transparent cap
  Dilation devices
   Push-type fixed-diameter dilators
   Hurst and Maloney dilators
   Savary-type dilators
   American Dilation System dilators
   TTS fixed diameter dilators
   Threaded-tip stent retrievers
   Radial expanding balloon dilators
   TTS dilators
  Achalasia balloon dilators
Outstanding issues and future trends
  Fiberoptic imaging
   Teaching attachments and photography
   Image capture
   Standardized image terminology
   Structured reporting
   The opportunities and challenges of the digital revolution
Digital imaging
  Imaging the gastrointestinal tract using a videoendoscope requires several steps
  Color models
Digitization of color
Color depth
Pixel density
File size
  What detail is needed?
  File compression
  Compression techniques
   Lossless compression
   Lossy compression
  Image file formats
  Color and black and white compression
  JPEG 2000 and beyond
DICOM standard
  Information Objects
   Patient name attributes
  DICOM conformance
  DICOM in endoscopy
  Expanding the scope of DICOM
How much compression is clinically acceptable?
  Studies of compression acceptability
   Vakil and Bourgeois
   Kim (personal communication)
  Developments in compression
Still pictures or live video?
  Video storage developments
What images should be recorded in practice?
  Lesion documentation
  Recording negative examinations
  Structured image documentation
  Costs of image documentation
Image enhancement
  Color manipulation
  Narrow band imaging and spectroscopy
Terminology standardization
  OMED standardized terminology
  Minimal standard terminology—MST
   Problems with MST
Outstanding issues and future trends
Editor's note
Relevant thermal effects in biological tissues
  Thermal devitalization
  Thermal coagulation
  Thermal desiccation
  Thermal carbonization
  Thermal vaporization
Generation of temperature in thermal tissue
  Heater probe
  High-frequency surgery
   General principles of high-frequency electric devices
   Electric arcs
Principles of high-frequency surgical coagulation
  Monopolar coagulation instruments
  Electro-hydro-thermo probes
  Bipolar coagulation instruments
Principles of high-frequency surgical cutting with particular regard to polypectomy
Technical aspects of polypectomy
  Polypectomy snares
  The polypectomy snare handle
  Polypectomy snare catheters
Safety aspects of high-frequency surgery
Argon plasma coagulation
  The principle of argon plasma coagulation
  Equipment for argon plasma coagulation
  Safety aspects of argon plasma coagulation
  Principle of Nd:YAG laser
  Specific characteristics of Nd:YAG lasers in flexible endoscopy
Safety aspects of Nd:YAG laser in flexible endoscopy
Sterilization and disinfection
  High-level disinfection
  What level of disinfection is required?
   Critical items
   Semi-critical items
  The practical problem
  The organisms
  The critical points in reprocessing
Risks of infections associated with endoscopic procedures
  Mechanisms of infection
  Clinical infections
   Infecting organisms
   Vegetative bacteria
   Clostridium difficile
   Mycobacterium tuberculosis
   Atypical mycobacteria
   Serratia marcescens
   Helicobacter pylori
   Human immunodeficiency virus (HIV)
   Hepatitis B
   Hepatitis C (HCV)
   What to do in practice about CJD?
   New variant CJD (vCJD)
   Other infections
  The endoscopic procedures
   Upper gastrointestinal endoscopy
   Lower gastrointestinal endoscopy
   Endoscopic retrograde cholangiopancreatography
   Percutaneous endoscopic gastrostomy
   Endoscopic ultrasound
  Host factors
   Immune competence
   The degree of tissue damage
   Intrinsic sources of infection
   Damaged valves and implants
Antibiotic prophylaxis for endoscopic procedures
  Principles of prevention of bacterial endocarditis
  High risk cardiovascular conditions [43]
  Moderate risk cardiovascular conditions [43]
  Recommendations for antibiotic prophylaxis
   Who should receive antibiotics?
   Clinical problems where opinions diverge
   What antibiotic regimen?
Antibiotic prophylaxis for ERCP
  Prophylactic antibiotic regimens for ERCP
Principles of effective decontamination protocols
  Cleaning is essential
  Effectiveness of recommended protocols
  Endoscope structure
   Common features
   External features
   Common internal features
   Special internal features
   Cleaning equipment
   Cleaning fluids
   Soaking time
   General maintenance
   Work areas
Reprocessing regimens
  Disinfect before and after procedures
  Manual cleaning
  Manual disinfection
  At the end of the list
  Endoscopic accessory equipment
   Cleaning accessories
   Special accessory items
   Sclerotherapy needles
   Water bottles and connectors
Problem areas in endoscope reprocessing
  Rinsing water
   Poor quality water
   Infections from rinsing water
   Bacteria free water
   Water testing
   Recommendations for rinsing water
Variation in cleaning and disinfection regimens depending upon the supposed infective status of the patient
Compliance with cleaning and disinfection protocols
The investigation of possible endoscopy infection transmission incidents
  Common causes
  Golden rules for investigating potential infection incidents
  The investigation process
  Transmission of viral disease
Automatic flexible endoscope reprocessors (AFERs)
  Machine design and principles
   Water supply
   Alarm function
   Fume containment
   Disinfectant supply
   Reprocessing time
   AFERs cannot guarantee to sterilize endoscopes
   Plumbing pathway
   Rinse and dry cycle
   Regular bacteriological surveillance
Quality control in endoscope reprocessing
  Quality control measures
Microbiological surveillance in endoscopy
  Testing procedures
  Interpretation of cultures
  Microbiological surveillance of AFERs
Outstanding issues and future trends
The contract with the patient; informed consent
  Educational materials
What are 'risks' and 'complications'?
  Threshold for 'a complication'
  Timing of unplanned events
  Direct and indirect events
  Data set for unplanned events
General issues of causation and management
  Technical and cognitive performance
  Fitness for procedures
   ASA score
   Other risk indices
  Prompt recognition and management
   Act promptly
  Specific unplanned events
   Failure to diagnose
   Risk factors
   Risk factors
   Cardiopulmonary and sedation complications
   Allergic reactions
   IV site issues
   Miscellaneous and rare events
Preventing unplanned events
Outstanding issues and future trends
Gastroenterologist–pathologist communication
  Endoscopist communication responsibility
  Pathologist communication responsibility
  Question-orientated approach
  Common terminology
Endoscopic biopsy specimens
  Specimen handling and interpretation issues
   Number of biopsies per container
   Tissue processing
   Prep-induced artifact
   Endoscopy-induced artifacts
   Biopsy-induced artifacts
   Crush artifact
   Burn/cautery artifact
   Endoscopic mucosal resection
   Core biopsy
  Regular stains
Exfoliative and fine-needle cytology
  Specimen handling; staining and fixation
   Cytological diagnosis
  Fine-needle aspiration
Organ system overview
   Where and when to biopsy
   Gastroesophageal reflux disease
   Barrett's esophagus
   Infective esophagitis
   Herpes simplex virus
   Adenocarcinoma and squamous cell carcinoma
   Where and when to biopsy
   Inflammatory conditions; gastritis
   H.pylori gastritis
   Hypertrophic folds
   Mass lesions
  Small bowel
   Celiac sprue
   Infective enteropathies
   Whipple's disease
   Mycobacterium avium–intracellulare
   Giardia lamblia
   Mass lesions
   Defining 'normal'
   Inflammatory colitides
   Normal colonoscopy
   Abnormal colonoscopy
   Inflammatory bowel disease
   Pseudomembranous colitis
   Ischemic colitis
   Mass lesions
Special stains
  Histochemical stains
  Immunohistochemical stains
  In situ hybridization
  Flow cytometry
  Electron microscopy
  Molecular pathology
Outstanding issues and future trends
The endoscopy facility and personnel
  Endoscopy facility
   Endoscopy instruments
   Ancillary equipment
   The endoscopist
   Nursing and ancillary personnel
The pediatric patient and procedural preparation
  Patient preparation
   Psychological preparation
   Medical preparation
   Recommendations for fasting
   Bowel preparation
   Antibiotic prophylaxis
  Informed consent
Endoscopic procedures currently performed in pediatric patients
  Indications and limitations
  Patient sedation
  Endoscopic technique
   Therapeutic endoscopy
   Other endoscopic modalities
   Small bowel enteroscopy
   Wireless capsule endoscopy
   Endoscopic ultrasonography
   Endoscopic retrograde cholangiopancreatography (ERCP)
Selected gastrointestinal pathologies in pediatric patients
  Eosinophilic esophagitis
  Food allergic enteropathy and colitis
  Foreign body ingestion
  Helicobacter pylori gastritis
  Polyps in the pediatric patient
  Lymphonodular hyperplasia
Outstanding issues and future directions
General principles of endoscopy training
  Traditional standard means of instruction
   Is self-teaching still acceptable?
  What to teach and how to teach it
  Defining competency and how to access it
   Linking diagnosis and therapy
   How competent?
   Varying rates of learning
   Learning beyond the training period
Training and competency in specific endoscopic procedures
  Esophagogastroduodenoscopy (EGD)
   Published guidelines for training in EGD
   Defining competence for EGD
   Data on acquisition of competency in diagnostic EGD
   Competency and EGD outcome
  Therapeutic EGD techniques
   Standard upper GI endoscopy techniques
   Hemostasis techniques
   Bleeding team
   Retaining competence
   Other specialized therapeutic upper GI endoscopy techniques
  Flexible sigmoidoscopy
   Published guidelines for training in flexible sigmoidoscopy
   Published guidelines for training in colonoscopy
   Defining competence for colonoscopy
   Technical components
   Cognitive objectives
   Minimum training requirements to achieve competency for colonoscopy
   The Cass study
   Competency and colonoscopy outcome
   Acceptable outcomes
   Rate of skills acquisition for colonoscopy
   Cases per week
   Too many cases?
  Therapeutic colonoscopy (biopsy, polypectomy, hemostasis techniques, stricture dilation, stent deployment)
   Standard therapeutic techniques (integral to performance of diagnostic colonoscopy)
   Advanced therapeutic colonoscopy techniques
  Diagnostic and therapeutic ERCP
   Published guidelines for training in ERCP
   Non-technical training
   Defining competence for ERCP
   Technical success
   Varying case difficulty
   Minimum training requirements to achieve competency for ERCP
   Case numbers
   What is a case?
   Competency and ERCP outcome
   Improving after training
   Annual volume
   Competence affects complication rates
   Rate of acquisition of ERCP skills
   Therapeutic ERCP
   Rate of acquisition of therapeutic skills
  Diagnostic and therapeutic EUS
   Defining competency in EUS
   Learning curve for EUS
   Therapeutic EUS
   EUS training opportunities
Complementary methods for instructions in GI endoscopy
  Advances in didactic methods
   Group instruction
   Laboratory demonstrations
  Endoscopy simulators
   Static models
   Courses with static models
   Ex vivo artificial tissue models: the 'phantom' Tübingen models
   Ex vivo animal tissue simulators: EASIE and Erlangen models
   Live animals
   Computer simulation
   GI Mentor™
   Current status of simulators
   Costs of simulators
   EUS models and simulators
  Use of training resources: summary
Endoscopy training 2010—a glimpse into the future
Credentialing and granting of privileges
   ASGE guidelines
Renewal of privileges and privileging in new procedures
  New procedures
Privileging for non-gastroenterologists and non-physician providers
The future of credentialing and privileging
  The use of new technology for credentialing
The role of endoscopic societies in training and credentialing
  Society courses
  Hands-on courses
  Research in training
  Influencing credentialing
Outstanding issues and future trends
Achieving competence—the goal of training
What experience is necessary in training? The fallacy of numbers
Beyond numbers: tools to measure competence
What level of competence is good enough? How is it recognized?
Endoscopic performance beyond training
Issues in measuring endoscopic performance
The report card agenda
The quality of endoscopy units
Outstanding issues and future trends
Most endoscopists are not interested
Is the problem declining?
Newly recognized infections
Compliance with guidelines
What can be done to remedy this sorry state of affairs?
  Infection control staff
  Microbiological surveillance
   British practice
The role of industry
Manual cleaning is key

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