Antimicrobial efficacy of endoscopic disinfection procedures: a controlled, multifactorial investigation

Decellularization of submillimeter-diameter vascular scaffolds using peracetic acid

Various decellularization methods for allogenic and xenogenic bioscaffolds have been previously reported; however, decellularization methods for very thin (submillimeter-diameter) vascular tissues have not been discussed well. In this study, rat tail arteries (inner diameter, 0.6 mm) were decellularized with peracetic acid (PAA) and DNase I. PAA treatment is expected not only to disrupt cell membranes which improves the decellularization efficiency in the subsequent DNase treatment, but also to sterilize vascular scaffolds. We succeeded in adequate cell removal by immersing in 0.3% isotonic PAA solution and subsequent washing with DNase solution. For the DNase washing process, the perfusion method was superior in terms of cell removal to the static immersion method. Graft lumen was modified with a peptide composed of a collagen binding sequence and endothelial progenitor cell-binding sequence, (Pro-Hyp-Gly)₇-Gly-Gly-Gly-Arg-Glu-Asp-Val, as previously reported. They were patent in rat allogeneic transplantation model for 2 weeks, but unexpectedly resulted in graft rupture or tear formation, thereafter, suggesting reduced mechanical strength of the decellularized scaffolds. Histology showed that the thickness of the extracellular matrix (ECM) was decreased by the perfusion of the DNase solution. The method of combination of PAA and DNase was not necessarily optimal for the decellularization of very thin vascular tissues. The decellularization method is a compromise between effective cell removal and maintenance of the ECM nature. Since the acceptability of ECM denaturation by the host tissue highly depends on individual cases, decellularization methods should be carefully selected according to the type of target tissue and its intended use.

Guidelines for standardizing cleansing and disinfection of gastrointestinal endoscopes

As part of the activities toward standardizing endoscopy procedures, the Japan Gastroenterological Endoscopy Society has prepared guidelines for cleansing and disinfection of gastrointestinal endoscopes. The environment of gastrointestinal endoscopy differs between Japan and advanced Western countries. In advanced Western countries, gastrointestinal endoscopy is performed almost exclusively at specialized facilities, where strict provisions are observed for cleansing and disinfecting endoscopes. In Japan, however, gastrointestinal endoscopy is performed even in small clinics, and the annual number of gastrointestinal endoscopy cases is enormous. In addition, the method for cleansing and disinfecting endoscopes differs among hospitals. Although there is a distinct lack of evidence for how gastrointestinal endoscopes are cleaned and disinfected, it is necessary to standardize the method for doing so to advance the field of endoscopic medicine.

Guidelines for diagnostic flexible bronchoscopy in adults: Joint Indian Chest Society/National College of chest physicians (I)/Indian association for bronchology recommendations

Flexible bronchoscopy (FB) is commonly performed by respiratory physicians for diagnostic as well as therapeutic purposes. However, bronchoscopy practices vary widely across India and worldwide. The three major respiratory organizations of the country supported a national-level expert group that formulated a comprehensive guideline document for FB based on a detailed appraisal of available evidence. These guidelines are an attempt to provide the bronchoscopist with the most scientifically sound as well as practical approach of bronchoscopy. It involved framing appropriate questions, review and critical appraisal of the relevant literature and reaching a recommendation by the expert groups. The guidelines cover major areas in basic bronchoscopy including (but not limited to), indications for procedure, patient preparation, various sampling procedures, bronchoscopy in the ICU setting, equipment care, and training issues. The target audience is respiratory physicians working in India and well as other parts of the world. It is hoped that this document would serve as a complete reference guide for all pulmonary physicians performing or desiring to learn the technique of flexible bronchoscopy.

Quality indicators in digestive endoscopy: introduction to structure, process, and outcome common indicators

The general goal of the project wherein this paper is framed is the proposal of useful quality and safety procedures and indicators to facilitate quality improvement in digestive endoscopy units. This initial offspring sets forth procedures and indicators common to all digestive endoscopy procedures. First, a diagram of pre- and post-digestive endoscopy steps was developed. A group of health care quality and/or endoscopy experts under the auspices of the Sociedad Española de Patología Digestiva (Spanish Society of Digestive Diseases) carried out a qualitative review of the literature regarding the search for quality indicators in endoscopic procedures. Then, a paired analysis was used for the selection of literature references and their subsequent review. Twenty indicators were identified, including seven for structure, eleven for process (five pre-procedure, three intra-procedure, three post-procedure), and two for outcome. Quality of evidence was analyzed for each indicator using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) classification.

Is peracetic acid suitable for the cleaning step of reprocessing flexible endoscopes?

The bioburden (blood, protein, pathogens and biofilm) on flexible endoscopes after use is often high and its removal is essential to allow effective disinfection, especially in the case of peracetic acid-based disinfectants, which are easily inactivated by organic material. Cleaning processes using conventional cleaners remove a variable but often sufficient amount of the bioburden. Some formulations based on peracetic acid are recommended by manufacturers for the cleaning step. We performed a systematic literature search and reviewed the available evidence to clarify the suitability of peracetic acid-based formulations for cleaning flexible endoscopes. A total of 243 studies were evaluated. No studies have yet demonstrated that peracetic acid-based cleaners are as effective as conventional cleaners. Some peracetic acid-based formulations have demonstrated some biofilm-cleaning effects and no biofilm-fixation potential, while others have a limited cleaning effect and a clear biofilm-fixation potential. All published data demonstrated a limited blood cleaning effect and a substantial blood and nerve tissue fixation potential of peracetic acid. No evidence-based guidelines on reprocessing flexible endoscopes currently recommend using cleaners containing peracetic acid, but some guidelines clearly recommend not using them because of their fixation potential. Evidence from some outbreaks, especially those involving highly multidrug-resistant gram-negative pathogens, indicated that disinfection using peracetic acid may be insufficient if the preceding cleaning step is not performed adequately. Based on this review we conclude that peracetic acid-based formulations should not be used for cleaning flexible endoscopes.

Quality assurance in endoscopy nursing

Since the 1960s quality assurance has become an integral part of medicine and nursing. The aims of quality assurance cover patient and staff safety and satisfaction, economical factors and the implementation of health care policy. Endoscopy units can be established in hospitals, primary care or ambulatory endoscopy centres. The quality of endoscopy facilities should be the same irrespective where endoscopy is carried out. Endoscopy staff is responsible for individualised, comprehensive patient care, technical assistance including reprocessing, documentation and management of endoscopy units. Quality criteria for endoscopy nursing cover pre, intra and post procedure care. However, a complete separation between clinical medical and nursing outcome criteria is often difficult in Endoscopy, as the clinical interventions are a combination of both medical and nursing actions. It is the combined effort of all staff with the support from the health care provider that leads to a high quality of patient care in Endoscopy.

Health care-associated transmission of hepatitis B and C viruses in endoscopy units

The risk for potential transmission of infectious agents during gastrointestinal (GI) endoscopy is concerning for patients and physicians. However, the instance of infection transmission remains rare after GI endoscopy procedures, with an estimated frequency of 1 in 1.8 million procedures. Endoscopy-related infection may occur when microorganisms are spread or transmitted from patient to patient by contaminated endoscopic or accessory equipments; from the GI tract through the bloodstream during endoscopy to susceptible organs or prostheses, or spread to adjacent tissues that are breached as a result of the endoscopy procedure; or from patients to endoscopy personnel and perhaps from endoscopy personnel to patients. Proper cleaning, disinfection, and reprocessing of endoscopies and accessories, and appropriate administration of intravenous drugs help to minimize the risk for infection transmission.

[Five years of the Robert Koch Institute guidelines for reprocessing of flexible endoscopes. A look back and a look forward]

In a short review the national and international reception of the German guidelines for reprocessing flexible endoscopes is presented. The recommendations of the guidelines are discussed in view of recent knowledge on old problems such as prion inactivation and new infectious diseases and new microorganisms such as SARS, avian influenza and C. difficile. New disinfectants and new methods for endoscope disinfection are mentioned, the importance of careful cleaning is underlined. The German guidelines of the Robert Koch Institute and the US Multi-Society guidelines, published in 2003, are compared. The discrepancies concerning recommendations for water quality for final rinsing and need of microbiological controls of endoscope reprocessing are stressed. Aspects not mentioned in the German guidelines, e.g. duration of storage after reprocessing and risk of infection transmission by the endo-washer, are discussed.

Preclinical characterization of the Spyglass peroral cholangiopancreatoscopy system for direct access, visualization, and biopsy

BACKGROUND

Current cholangioscopes are restricted to 2 deflection angles and require more than 1 operator. The newly developed Spyglass peroral cholangiopancreatoscopy system provides 4-way deflected steering by a single operator.

OBJECTIVE

To evaluate access and biopsy in all simulated biliary-duct quadrants with the Spyglass system, high-level disinfection of the reusable Spyglass optical probe, and feasibility of in vivo biopsy.

DESIGN

Laboratory simulations comparing biliary-duct access and biopsy with the Spyglass versus a conventional system, laboratory determination of high-level disinfection effectiveness, and observational investigation of biopsies in a porcine model.

SETTING

Research laboratories.

MAIN OUTCOME MEASUREMENTS

Rate ratios (RR) and 95% confidence intervals (CI) for successful access to all quadrants and simulated biopsy.

RESULTS

Success rates for access in all quadrants were significantly higher with the Spyglass system than with the control system, both without (RR 1.71, 95% CI 1.39-2.29) and with (RR 2.00, 95% CI 1.56-2.78) biopsy forceps loaded. Higher success rates were also attained by using the Spyglass system to access biopsy targets (RR 2.09, 95% CI 1.60-2.91) and to perform simulated biopsies (RR 2.94, 95% CI 2.05-4.52). Microbial species log reductions of 6.0 to 7.0 were achieved by high-level disinfection of Spyglass optical probes. In 31 in vivo porcine biopsies yielding adequate gross specimens, the quality for histologic examination was excellent to adequate for 90% of specimens.

LIMITATIONS

Study procedures were performed by a single nonblinded operator. All data were collected ex vivo or in animals, and clinical applicability remains to be determined.

CONCLUSIONS

The Spyglass system allows access and biopsy in all quadrants and merits clinical investigation.

Exogenous endoscopy-related infections, pseudo-infections, and toxic reactions: clinical and economic burden

OBJECTIVES

The objective of this study was to analyze the characteristics and costs of exogenous endoscopy-related infections, pseudo-infections, and toxic reactions in the US.

METHODS

A systematic review of the scientific literature published between 1966 and 2005 was conducted in Medline. Data collection was based on a prospective protocol developed by the authors.

RESULTS

The literature review included 70 outbreaks described in 64 scientific articles. Bronchoscopy accounted for half of all reported outbreaks. Inadequate decontamination practices were the leading cause of contamination; equipment malfunction became the second leading cause of contamination during the period 1990-2004. More than 91% of the infections identified could be prevented by health care providers if quality control systems are improved and implemented. The available economic information concerning exogenous endoscope related events is very limited. A model for the analysis of the economic burden of exogenous endoscopy-related events is proposed.

CONCLUSIONS

Proper decontamination practices, the use of protective sheaths, and the improvement of surveillance systems could reduce the clinical and economic burdens associated with exogenous endoscopy-related events.

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Efficacy of electrolyzed acid water in reprocessing patient-used flexible upper endoscopes: Comparison with 2% alkaline glutaraldehyde

BACKGROUND AND AIM

Two percent glutaraldehyde, the most widely used liquid chemical germicide (LCG), may be hazardous to patients and medical personnel. Alternatives to glutaraldehyde, such as electrolyzed acid water (EAW), are being developed, but data from well-controlled studies with patient-used endoscopes are rare. The purpose of the present paper was to evaluate the high-level disinfection capability of EAW and compare it with glutaraldehyde.

METHODS

A random sample of 125 endoscopes was collected immediately after upper endoscopic examination. After careful manual cleaning, endoscopes were divided into a glutaraldehyde and EAW group. After the disinfection procedure, samples from working channel (S-1), insertion tube (S-2), umbilical cord (S-3), and angulation knob (S-4) were taken and cultured. Another twenty endoscopes were experimentally contaminated with hepatitis B virus (HBV) and samples were collected after contamination (T-1), after manual cleaning (T-2), and after final disinfection (T-3). Polymerase chain reaction (PCR) for HBV-DNA was performed.

RESULTS

In the EAW group, culture-positive rates were 3.2% in S-1, 9.5% in S-2, 3.2% in S-3, and 27.0% in the S-4 samples. There was no significant difference between the EAW and glutaraldehyde groups for all sampling sites. However, in both groups, disinfection of the angulation knobs (S-4) was less efficient than the others. For the T-1 site, HBV-DNA was detected from all of them, and in 95% (19/20) of T-2. However, HBV-DNA was not detected from T-3 samples.

CONCLUSIONS

Electrolyzed acid water is as efficient as glutaraldehyde in eliminating bacteria from patient-used endoscopes. After disinfection procedures using both methods, HBV-DNA was not detected from any endoscopes experimentally contaminated with HBV-positive mixed sera. However, some bacteria may remain on the surface of the endoscopes. Therefore, more careful precleaning of the endoscopes may help achieve high-level disinfection in the clinical setting.

Disposable versus reusable biopsy forceps in GI endoscopy: a cost-minimization analysis

BACKGROUND

The use of disposable biopsy forceps seems to be effective and safer than reusable biopsy forceps with respect to the risk of infection transmission. The results of cost analysis studies comparing reusable versus disposable biopsy forceps are conflicting. This study compared the cost of reusable versus disposable biopsy forceps.

METHODS

A cost-minimization analysis was carried out from the viewpoint of a hospital. Direct costs were included. The study design was retrospective. For reusable biopsy forceps, the evaluation of costs included purchase prices, cleaning (chemicals, equipment, technician time), and a fee for sterilization in a centralized facility. The cost evaluation for disposable biopsy forceps included acquisition and destruction costs. Costs were expressed in United States dollars.

RESULTS

The mean number of uses was approximately 90 per reusable forceps. The cost per use of reusable biopsy forceps was 6.84 US dollars (acquisition 3.59 US dollars, cleaning 2.28 US dollars, centralized sterilization fee 0.97 US dollars). The cost per use of disposable biopsy forceps varied from 10.72 US dollars to 15.63 US dollars. Additional cost per use of disposable biopsy forceps ranged from 3.88 US dollars to 8.79 US dollars.

CONCLUSIONS

From a strictly economic point of view, the use of reusable biopsy forceps is advantageous. However, additional factors should be considered. It would be essential to take into account the potential risk of infectious disease transmission related to the use of both types of forceps, which remains uncharacterized.

Multi-society guideline for reprocessing flexible gastrointestinal endoscopes. Society for Healthcare Epidemiology of America

Flexible gastrointestinal endoscopy is a valuable diagnostic and therapeutic tool for the care of patients with gastrointestinal and pancreaticobiliary disorders. Compliance with accepted guidelines for the reprocessing of gastrointestinal endoscopes between patients is critical to the safety and success of their use. When these guidelines are followed, pathogen transmission can be effectively prevented. Increased efforts and resources should be directed to improve compliance with these guidelines. Further research in the area of gastrointestinal endoscope reprocessing should be encouraged. The organizations that endorsed this guideline are committed to assisting the FDA and manufacturers in addressing critical infection control issues in gastrointestinal device reprocessing.

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Virus safety of a porcine-derived medical device: evaluation of a viral inactivation method

The goal of this study was to evaluate the efficacy of a virus-inactivating process for use during the preparation of porcine-derived extracellular matrix biomaterials for human clinical implantation. Porcine small intestine, the source material for the tissue-engineered, small intestinal submucosa (SIS) biomaterial, was evaluated. Relevant enveloped, non-enveloped, and model viruses representative of different virus families were included in the investigation: porcine parvovirus (PPV), porcine reovirus, murine leukemia retrovirus (LRV), and porcine pseudorabies (herpes) virus (PRV). Samples of small intestine were deliberately inoculated with approximately 1 x 10(7) plaque-forming units (PFU) of virus which were thereafter exposed to a 0.18% peracetic acid/4.8% aqueous ethanol mixture for time periods ranging from 5 minutes to 2 hours. Enveloped viruses were more easily inactivated than non-enveloped viruses, but material processed for 30 minutes or longer inactivated all of the viruses. D(10) values were calculated and used to extrapolate the extent of inactivation after 2 hours. Viral titers were reduced by more than 14.0 log(10) PPV, 21.0 log(10) reovirus, 40.0 log(10) PRV, and 27.0 log(10) LRV, meeting international standards for viral sterility. These results demonstrate that treatment of porcine small intestine with a peracetic acid/ethanol solution leads to a virus-free, non-crosslinked biomaterial safe for xenotransplantation into humans.

Establishing the shelf life of flexible colonoscopes

This study was designed to establish a shelf life for processed (peracetic acid) flexible colonoscopes and to demonstrate the adequacy of manual cleaning procedures. The study challenges current practice in Australia where endoscopes are routinely reprocessed prior to use if the endoscope has been sitting at least overnight. The design was a simulated study in the clinical environment and involved artificial contamination of a colonoscope, cleaning validation, and a time series analysis after processing with peracetic acid in a Steris System 1 processor and drying with 100% isopropyl alcohol. The main outcome measure was the presence of bacteria in the internal channels of the colonoscope after cleaning and at 24 and 168 hours after processing with peracetic acid. The findings suggest that colonoscopes may be left for up to 1 week before needing to be reprocessed before use, provided all channels are thoroughly reprocessed and dried, resulting in cost savings and reduced wear and tear on the instruments. The findings also demonstrate the impact of providing feedback to staff on a regular basis about the efficacy of their cleaning techniques.

Nosocomial transmission of imipenem-resistant Pseudomonas aeruginosa following bronchoscopy associated with improper connection to the Steris System 1 processor

OBJECTIVE

To assess nosocomial transmission of imipenem-resistant Pseudomonas aeruginosa (IRPA) following bronchoscopy during August through October 1998.

DESIGN

Traditional and molecular epidemiological investigation of a case series.

SETTING

University-affiliated community hospital.

PATIENTS

18 patients with IRPA bronchial-wash isolates.

INTERVENTIONS

We reviewed clinical data, performed environmental cultures and molecular analysis of all IRPA isolates, and observed disinfection of bronchoscopes.

RESULTS

Of 18 patients who had IRPA isolated from bronchoscopic or postbronchoscopic specimens, 13 underwent bronchoscopy for possible malignancy or undiagnosed pulmonary infiltrates. Following bronchoscopy, 3 patients continued to have IRPA isolated from sputum and demonstrated clinical evidence of infection requiring specific antimicrobial therapy. The remaining 15 patients had no further IRPA isolated and remained clinically well 3 months following bronchoscopy. Pulsed-field gel electrophoresis revealed that all strains except one were >95% related. STERIS SYSTEM 1 had been implemented in July 1998 as an automatic endoscope reprocessor (AER) for all endoscopes and bronchoscopes. Inspection of bronchoscope sterilization cycles revealed incorrect connectors joining the bronchoscope suction channel to the STERIS SYSTEM 1 processor, obstructing peracetic acid flow through the bronchoscope lumen. No malfunction warning was received, and spore strips remained negative.

CONCLUSIONS

The similarity of diverse connectors and limited training by the manufacturer regarding AER for bronchoscopes were the two factors responsible for the outbreak. Appropriate connections were implemented, and there was no further bronchoscope contamination. We suggest active surveillance of all bronchoscopy specimen cultures, standardization of connectors of various scopes and automated processors, and systematic education of staff by manufacturers with periodic on-site observation.

Reprocessing of flexible endoscopes

Proper reprocessing of endoscopes prevents the risk of transmission of infection between patients. Meticulous mechanical cleaning is the most important step as it removes the majority of the contaminating bacteria. It should be performed before manual or automatic disinfection. High-level disinfection involves total immersion of the endoscope in a liquid chemical germicide (LCG) at a preset temperature and concentration for a pre-determined period of time. Subsequent rinsing and drying are essential steps to remove the chemical solution and prevent bacterial colonization during storage. Endoscopy units that are used for more than 50 procedures per week may benefit from cleaning in an automatic endoscope reprocessor (AER). This allows automated exposure of the endoscope to the LCG with subsequent flushing and drying of the channels, and minimizes staff exposure to the LCG. Reprocessing should be performed by trained and accredited personnel according to written guidelines or standards of practice as defined by professional societies. Regular monitoring of the reprocessing process is important for quality control and in ensuring patients' safety.

Preventing nosocomial infections from gastrointestinal endoscopy

Gastrointestinal procedures have been associated with a wide range of infectious complications, including bacterial endocarditis. Although the rate of bacteremia from the patient's own flora is quite high after some procedures, only a few cases of endocarditis caused by gastrointestinal instrumentation have been reported. Because of the severity of the illness, however, antibiotic prophylaxis has been recommended for patients who are categorized as high risk for some procedures. Bacteremia and other infections, such as colitis, may also originate from a contaminated endoscope. To prevent such an occurrence, high-level disinfection has been recommended for gastrointestinal endoscopes. High-level disinfection includes manual cleaning of the endoscope, flushing of internal channels with a liquid chemical sterilant, and thorough rinsing and drying of internal lumens.