Detection of persistent vegetative bacteria and amplified viral nucleic acid from in-use testing of gastrointestinal endoscopes

Bacillus subtilis NDmed, a model strain for biofilm genetic studies

The Bacillus subtilis strain NDmed was isolated from an endoscope washer-disinfector in a medical environment. NDmed can form complex macrocolonies with highly wrinkled architectural structures on solid medium. In static liquid culture, it produces thick pellicles at the interface with air as well as remarkable highly protruding ''beanstalk-like'' submerged biofilm structures at the solid surface. Since these mucoid submerged structures are hyper-resistant to biocides, NDmed has the ability to protect pathogens embedded in mixed-species biofilms by sheltering them from the action of these agents. Additionally, this non-domesticated and highly biofilm forming strain has the propensity of being genetically manipulated. Due to all these properties, the NDmed strain becomes a valuable model for the study of B. subtilis biofilms. This review focuses on several studies performed with NDmed that have highlighted the sophisticated genetic dynamics at play during B. subtilis biofilm formation. Further studies in project using modern molecular tools of advanced technologies with this strain, will allow to deepen our knowledge on the emerging properties of multicellular bacterial life.

Effect of disinfectants and manual wiping for processing the cell product changeover in a biosafety cabinet

Introduction

The process of cell product changeover poses a high risk of cross-contamination. Hence, it is essential to minimize cross-contamination while processing cell products. Following its use, the surface of a biosafety cabinet is commonly disinfected by ethanol spray and manual wiping methods. However, the effectiveness of this protocol and the optimal disinfectant have not yet been evaluated. Here, we assessed the effect of various disinfectants and manual wiping methods on bacterial removal during cell processing.

Methods

The hard surface carrier test was performed to evaluate the disinfectant efficacy of benzalkonium chloride with a corrosion inhibitor (BKC + I), ethanol (ETH), peracetic acid (PAA), and wiping against Bacillus subtilis endospores. Distilled water (DW) was used as the control. A pressure sensor was employed to investigate the differences in loading under dry and wet conditions. The pre-spray for wiping was monitored by eight operators using a paper that turns black when wet. Chemical properties, including residual floating proteins, and mechanical properties, such as viscosity and coefficient of friction, were examined.

Results

In total, 2.02 ± 0.21-Log and 3.00 ± 0.46-Log reductions from 6-Log CFU of B. subtilis endospores were observed for BKC + I and PAA, respectively, following treatment for 5 min. Meanwhile, wiping resulted in a 0.70 ± 0.12-Log reduction under dry conditions. Under wet conditions, DW and BKC + I showed 3.20 ± 0.17-Log and 3.92 ± 0.46-Log reductions, whereas ETH caused a 1.59 ± 0.26-Log reduction. Analysis of the pressure sensor suggested that the force was not transmitted under dry conditions. Evaluation of the amount of spray by eight operators showed differences and bias in the spraying area. While ETH had the lowest ratio in the protein floating and collection assays, it exhibited the highest viscosity. BKC + I had the highest friction coefficient under 4.0-6.3 mm/s; however, that of BKC + I decreased and became similar to the friction coefficient of ETH under 39.8-63.1 mm/s.

Conclusions

DW and BKC + I are effective for inducing a 3-Log reduction in bacterial abundance. Moreover, the combination of optimal wet conditions and disinfectants is essential for effective wiping in specific environments containing high-protein human sera and tissues. Given that some raw materials processed in cell products contain high protein levels, our findings suggest that a complete changeover of biosafety cabinets is necessary in terms of both cleaning and disinfection.

Investigation of the Internal Conditions of 213 Reprocessed Endoscopic Channels

BACKGROUND AND AIMS

Studies have indicated that endoscope reprocessing failure might be attributed to internal damage or residual liquid in endoscopes. However, large-sample survey data on the internal conditions of endoscopic channels after reprocessing are lacking. This study used a borescope to investigate the internal cleanliness and damage of 213 endoscopic biopsy channels after reprocessing at the endoscopy center of the First Affiliated Hospital of Nanchang University, provided in theoretical basis for the efficacy of endoscope reprocessing and maintenance.

METHODS

A borescope was used to observe and analyze the inside of the endoscopic biopsy channel of 213 reprocessed endoscopes (in accordance with the Chinese health industry standard "Regulation for cleaning and disinfection technique of flexible endoscope (WS 507-2016). Each endoscope was observed for at least 10 minutes, and the results were recorded and evaluated by 5 researchers independently.

RESULTS

In all, 2504 images and 109 videos were recorded, and abnormal findings were classified into 10 categories: scratches (91.5%, 195/213), scratches with adherent peel (46.0%, 98/213), discolored areas (49.3%, 105/213), transparent drops (28.2%, 60/213), milky drops (23.9%, 51/213), white particles (46.9%, 100/213), attached materials (37.6%, 80/213), wear on metal parts (41.3%, 88/213), rust (23.9%, 51/213), and black spots (35.7%, 76/213). Among scratches, those in Teflon from 0-10 cm at the apex of the biopsy channel outlet and in metal from 0-5 cm at the biopsy channel inlet accounted for 58.4% (114/195) and 96.4% (188/195), respectively.

CONCLUSIONS

Scratches were the most common form of damage in the endoscopic biopsy channels investigated and were related to the use of endoscopic accessories and cleaning brush materials. The incidence of other abnormalities gradually increased with the duration of use and began to increase significantly after 18 months. All abnormalities have a certain impact on the quality of endoscope reprocessing. We recommend that a borescope be used to check the inside of endoscopic biopsy channels regularly to determine the damage and cleaning conditions and that these channels be reprocessed, repaired, or replaced in a timely manner.

Duodenoscope-Associated Infections: Update on an Emerging Problem

The duodenoscope is among the most complex medical instruments that undergo disinfection between patients. Transmission of infection by contaminated scopes has remained a challenge since its inception. Notable risk factors for pathogen transmission include non-adherence to disinfection guidelines, encouragement of biofilm deposition due to complex design and surface defects and contaminated automated endoscope reprocessors. The most common infections following endoscopy are endogenous infections involving the patient's own gut flora. Exogenous infections, on the other hand, are associated with contaminated scopes and can theoretically be prevented by effective reprocessing. Pseudomonas aeruginosa is currently the most common organism isolated from contaminated endoscopes. Of note, reports of multidrug-resistant duodenoscopy-associated outbreaks have surfaced recently, many of which occurred despite adequate reprocessing. The FDA and CDC currently recommend comprehensive cleaning followed with at least high-level disinfection for reprocessing of flexible GI endoscopes. Reports of duodenoscope-related outbreaks despite compliance with established guidelines have prompted professional and government bodies to revisit existing guidelines and offer supplementary recommendations for duodenoscope processing. For the purposes of this review, we identified reports of duodenoscope-associated infections from 2000 till date. For each outbreak, we noted the organisms isolated, the number of cases reported, any possible explanations of contamination, and the measures undertaken to end each outbreak. We have also attempted to present an overview of recent developments in this rapidly evolving field.

Recent Update on Microbiological Monitoring of Gastrointestinal Endoscopes after High-Level Disinfection

Endoscopy-related infections are important contributors to nosocomial infections. Endoscope reprocessing according to standard guidelines ensures high-level disinfection and prevents endoscopy-related infections. Microbiological surveillance may help in monitoring the effectiveness of gastrointestinal endoscope disinfection. The process involves microbial cultures and non-culture methods such as bioburden assays, adenosine triphosphate (ATP) bioluminescence, and quantitative polymerase chain reactions (PCRs). Surveillance culturing to monitor endoscopes after reprocessing has been recommended by a majority of organizations. Bioburden assays, ATP bioluminescence, and quantitative PCRs provide rapid and reliable measures. Each institution will have to try to establish its own surveillance guidelines.

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.

Biofilms of a Bacillus subtilis hospital isolate protect Staphylococcus aureus from biocide action

The development of a biofilm constitutes a survival strategy by providing bacteria a protective environment safe from stresses such as microbicide action and can thus lead to important health-care problems. In this study, biofilm resistance of a Bacillus subtilis strain (called hereafter ND_medical) recently isolated from endoscope washer-disinfectors to peracetic acid was investigated and its ability to protect the pathogen Staphylococcus aureus in mixed biofilms was evaluated. Biocide action within Bacillus subtilis biofilms was visualised in real time using a non-invasive 4D confocal imaging method. The resistance of single species and mixed biofilms to peracetic acid was quantified using standard plate counting methods and their architecture was explored using confocal imaging and electronic microscopy. The results showed that the ND_medical strain demonstrates the ability to make very large amount of biofilm together with hyper-resistance to the concentration of PAA used in many formulations (3500 ppm). Evidences strongly suggest that the enhanced resistance of the ND_medical strain was related to the specific three-dimensional structure of the biofilm and the large amount of the extracellular matrix produced which can hinder the penetration of peracetic acid. When grown in mixed biofilm with Staphylococcus aureus, the ND_medical strain demonstrated the ability to protect the pathogen from PAA action, thus enabling its persistence in the environment. This work points out the ability of bacteria to adapt to an extremely hostile environment, and the necessity of considering multi-organism ecosystems instead of single species model to decipher the mechanisms of biofilm resistance to antimicrobials agents.

Resistance of bacterial biofilms to disinfectants: a review

A biofilm can be defined as a community of microorganisms adhering to a surface and surrounded by a complex matrix of extrapolymeric substances. It is now generally accepted that the biofilm growth mode induces microbial resistance to disinfection that can lead to substantial economic and health concerns. Although the precise origin of such resistance remains unclear, different studies have shown that it is a multifactorial process involving the spatial organization of the biofilm. This review will discuss the mechanisms identified as playing a role in biofilm resistance to disinfectants, as well as novel anti-biofilm strategies that have recently been explored.

Automated endoscope reprocessors

The ASGE Technology Committee provides reviews of existing, new, or emerging endoscopic technologies that have an impact on the practice of GI endoscopy. Evidence-based methodology is used, with a MEDLINE literature search to identify pertinent clinical studies on the topic and a MAUDE (U.S. Food and Drug Administration Center for Devices and Radiological Health) database search to identify the reported complications of a given technology. Both are supplemented by accessing the "related articles" feature of PubMed and by scrutinizing pertinent references cited by the identified studies. Controlled clinical trials are emphasized, but in many cases data from randomized, controlled trials are lacking. In such cases, large case series, preliminary clinical studies, and expert opinions are used. Technical data are gathered from traditional and Web-based publications, proprietary publications, and informal communications with pertinent vendors. Technology Status Evaluation Reports are drafted by 1 or 2 members of the ASGE Technology Committee, reviewed and edited by the committee as a whole, and approved by the Governing Board of the ASGE. When financial guidance is indicated, the most recent coding data and list prices at the time of publication are provided. For this review, the MEDLINE database was searched through February 2010 for articles related to automated endoscope reprocessors, using the words endoscope reprocessing, endoscope cleaning, automated endoscope reprocessors, and high-level disinfection. Technology Status Evaluation Reports are scientific reviews provided solely for educational and informational purposes. Technology Status Evaluation Reports are not rules and should not be construed as establishing a legal standard of care or as encouraging, advocating, requiring, or discouraging any particular treatment or payment for such treatment.

The effect of multiple cycles of contamination, detergent washing, and disinfection on the development of biofilm in endoscope tubing

BACKGROUND

Patient soil and bacterial biofilm in patient-ready endoscope channels can adversely impact the efficacy of detergent and disinfectant, thereby increasing the risk of nosocomial infection. Biofilm bacteria are firmly attached to one another and to the substrate by exopolysaccharide, making them difficult to remove. We analyzed the effect of 20 wash/contamination cycles on biofilm formation.

MATERIALS

Pseudomonas aeruginosa biofilm-covered endoscope tubing was soaked in water (control), an enzymatic cleaner, or a nonenzymatic cleaner (Matrix) for 10 minutes and decontaminated in a washer-disinfector machine. Media containing P aeruginosa was then recycled to simulate contamination in clinical practice.

RESULTS

SEM analysis showed that loosely attached biofilm was removed under the high flow rates in the washer-disinfector. The control tubing remained 100% covered with biofilm, which became thicker with increased recontamination cycles. Washing in the enzymatic detergent retarded the redevelopment of biofilm. The nonenzymatic cleaner (Matrix) continued to remove more biofilm with an increasing number of wash/contamination cycles. At the 20th cycle, 90% of the tubing was biofilm-free.

CONCLUSION

Washing endoscopes under high flow rates with some detergents removes established biofilm and retards biofilm generation, emphasizing the importance of cleaning before disinfection. Continued research into the physicochemical mechanisms of biofilm adherence and removal is needed to optimize detergents.

Microbiologic profile of flexible endoscope disinfection in two Brazilian hospitals

BACKGROUND

[corrected] Endoscopes are routinely used in hospitals and clinics of the world and they can be potential sources of cross-infection when the decontamination process is unsuitable

AIM

The routines of flexible endoscope (bronchoscopes, esophagogastroduodenoscopes and colonoscopes) disinfection procedures used in two Brazilian university hospitals were evaluated during a 3-year period

METHODS

Aleatory samples from internal channels of endoscopes were collected after patient examination and after cleaning/disinfection procedures

RESULTS

A contamination >3 log10 was achieved in samples recovered from endoscopes after patient examination. These samples yielded gram-negative bacilli (n = 142: 56%), gram-positive cocci (n = 43: 17%), yeast cells (n = 43: 17%), and gram-positive bacilli (n = 26: 10%). Approximately, 72 out of 149 samples (48.32%) collected after undergoing the cleaning and disinfection procedures disclosed gram-negative bacilli (n = 55: 61%), gram-positive cocci (n = 21: 23%), gram-positive bacilli (n = 8: 9%) and yeast cells (n = 6: 7%). Esophagogastroduodenoscopes and colonoscopes were the most frequently contaminated devices. Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Enterobacter spp, Serratia marcescens, Proteus mirabilis, Citrobacter freundii, Staphylococcus aureus, Staphylococcus coagulase negative, Micrococcus luteus, Candida albicans, C. tropicalis, C. glabrata, C. guilliermondii, Bacillus spp and Corynebacterium spp were predominantly identified

CONCLUSION

Inappropriate cleaning and low times of disinfection were respectively the major factors associated with the presence of microorganisms in colonoscopes and esophagogastroduodenoscopes. By analyzing the identified germs, hospital disinfection was considered of either intermediate or poor level. After this investigation, both university centers improved their previous protocols for disinfection and conditions for reprocessing endoscopes.

Inactivation of human adenovirus genome by different groups of disinfectants

Human adenoviruses are model viruses for testing the virucidal efficacy of disinfectants. However, a recent study has shown that the chemical sensitivity of adenovirus serotypes varies significantly, possibly due to the composition of the viral capsid and/or the resistance of nucleic acids. We have investigated the effect of molecular changes in the viral genome of the human adenovirus subgenera C and D. A common oligonucleotide fragment within the hexon gene was amplified by polymerase chain reaction (PCR) after exposure to liposomal povidone-iodine (PVP-I), peracetic acid (PAA), and formaldehyde. The findings were compared with infectivity in cell cultures. PVP-I (0.125%) destroyed the infectivity of most serotypes within 60 min. However, PCR revealed no destruction of the adenoviral genome in most serotypes, even after exposure to higher PVP-I concentrations. PAA (0.5%) failed to inactivate the hexon gene of adenovirus types 22 and 44. Furthermore, the hexon gene of adenovirus type 22 was not altered by 0.7% formaldehyde. In conclusion, the genomes of human adenoviruses show considerably more chemical resistance than the complete viral particle. The molecular resistance of individual serotypes also varies. However, there was no clear correlation between the differences in the effect of disinfectants on infectivity of the complete viral particle and destruction of the viral genome.

Current issues in endoscope reprocessing and infection control during gastrointestinal endoscopy

The purpose of this article is to review the evidence regarding transmission of infection during gastrointestinal endoscopy, factors important in endoscope reprocessing and infection control, areas to focus on to improve compliance, and recent developments and advances in the field.

A prospective study of the efficacy of routine decontamination for gastrointestinal endoscopes and the risk factors for failure

BACKGROUND

Patient-ready endoscopes were monitored over an 80-week period to determine the efficacy of decontamination procedures in a busy endoscopy center. Decontamination failure was related to patient and procedural parameters.

METHODS

Samples from patient-ready endoscopes were cultured aerobically and anaerobically and subjected to polymerase chain reaction (PCR) to detect hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV. PCR to detect coliforms from 109 culture negative washes was used as a surrogate marker for biofilm in endoscopes. PCR was used to detect the presence of Helicobactor pylori in endoscopes used on infected patients. Procedural information such as biopsy retrieval, endoscope number, diagnosis, attending personnel, and decontamination system procedures was collected.

RESULTS

Gastroscopes (n = 1,376) and colonoscopes (n = 987) were equally contaminated (1.8% vs 1.9%, respectively) with low numbers of organisms commonly isolated from the nasopharynx and/or feces. Only 1 wash contained viral nucleic acid (HCV). There was a significant correlation (P < .001) between the number of times a patient-ready endoscope was contaminated and its frequency of use. Colonoscopes used on patients with gastrointestinal disease were significantly more likely to remain contaminated through the decontamination process (P < .05). All other patient, staff, and decontamination system parameters remained not statistically significant. Coliform DNA was detected in 40% of culture-negative washes collected from patient-ready endoscopes, suggesting the presence of biofilm. No H pylori DNA was detected.

CONCLUSION

Recommended decontamination procedures do not entirely eliminate persistence of low numbers of organisms on a few endoscopes, but this is unlikely to cause serious consequences in patients. Bacterial biofilm is difficult to remove and may explain this low-level persistence.

Gastrointestinal endoscopy decontamination failure and the risk of transmission of blood-borne viruses: a review

The risk of blood-borne virus transmission with an inadequately decontaminated endoscope during gastrointestinal endoscopy remains unclear, although it is likely to be low. A systematic review of the literature was undertaken to determine previous episodes of blood-borne virus transmission in these circumstances. In total, 31 articles were included in this review. No articles relating to possible transmission of human immunodeficiency virus were identified. The articles included were generally case series or case reports and were written prior to the comprehensive endoscope decontamination guidelines in use today. The results suggest that hepatitis B and hepatitis C transmission are low during endoscopy with an inadequately decontaminated endoscope.

Flexible naso-endoscopic decontamination—rationalizing the next step forward

Naso-endoscopes are important tools in the everyday practice of otolaryngology. However, cleaning methods have not yet been standardized. The aims of this article are to assess the degree of variation in practice both within and outside the UK, and to propose explanations why standard national and international guidelines have not been forthcoming. It is hoped that the systematic identification of the problems facing health authorities will lead to a better understanding of the task at hand, and bring us closer to drawing up a more specific standard for 'best possible' practice.

Risk of hepatitis B virus transmission by diagnostic hysteroscopy

Few data are available in the literature concerning the efficacy of standard hysteroscope disinfection procedures to prevent hepatitis B transmission. The aim of the present study was to determine the risk of hepatitis B virus (HBV) transmission during hysteroscopy among anti-HBc-seropositive women. Serum and hysteroscopic samples were collected from 62 women after diagnostic hysteroscopy. All samples were tested for serologic HBV markers. Polymerase chain reactions (PCR) were carried out to amplify regions C and S of the viral genome and only samples amplified by both pairs of primers were considered to be positive. Anti-HBc was repeatedly reactive in 48 (77%) of 62 serum samples, and HBsAg was detected in 8 (13%). At least one HBV serologic marker was found in 49 (79%) samples. Only one sample was HBsAg positive and anti-HBc negative. HBV-DNA was detected by PCR in 7 serum samples but in only 3 hysteroscopic samples obtained just after hysteroscopy. It is noteworthy that high levels of anti-HBc IgM were detected in one HBsAg-negative patient who showed an HBV-DNA-positive hysteroscopic sample. An elevated sample/cut-off ratio for anti-HBc IgM suggests recent infection and reinforces the need for testing for HBsAg and anti-HBc before hysteroscopy, since acute hepatitis B can be clinically asymptomatic. Viral DNA was not detected in any hysteroscopic samples collected after washing and disinfecting procedures with glutaraldehyde. We conclude that HBV-DNA can be found in the hysteroscope soon after hysteroscopy, but standard disinfecting procedures are effective in viral removal.

Blood-borne viruses and their survival in the environment: is public concern about community needlestick exposures justified?

BACKGROUND

More than 30 million needle syringes are distributed per year in Australia as a component of harm-reduction strategies for injecting drug users (IDU). Discarded needle syringes create considerable anxiety within the community, but the extent of needlestick injuries and level of blood-borne virus transmission risk is unclear. We have undertaken a review of studies of blood-borne virus survival as the basis for advice and management of community needlestick injuries.

METHODS

A Medline review of published articles on blood-borne virus survival and outcome from community injuries.

RESULTS

Hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) can all survive outside the human body for several weeks, with virus survival influenced by virus titer, volume of blood, ambient temperature, exposure to sunlight and humidity. HBV has the highest virus titers in untreated individuals and is viable for the most prolonged periods in needle syringes stored at room temperature. However, prevalence of HBV and HIV are only 1-2% within the Australian IDU population. In contrast, prevalence of HCV is 50-60% among Australian IDUs and virus survival in needle syringes has been documented for prolonged periods. There have been no published cases of blood-borne virus transmission following community needlestick injury in Australia.

CONCLUSION

The risk of blood-borne virus transmission from syringes discarded in community settings appears to be very low. Despite this, procedures to systematically follow up individuals following significant needlestick exposures sustained in the community setting should be developed.

Surveillance cultures to monitor quality of gastrointestinal endoscope reprocessing

OBJECTIVES

High-level disinfection of GI endoscopes can be reliably obtained under controlled conditions with approved reprocessing methods. However, there are scant data regarding the effectiveness of these methods in clinical practice and no published methods of verification. The purpose of this study is to review retrospectively the results of environmental cultures of flexible endoscopes and to analyze the pattern of results.

METHODS

Cultures of selected GI endoscopes listed as ready to use were obtained by adding 5-15 ml of trypticase soy broth or saline or 30-50 ml of sterile water to the biopsy channel of an endoscope. This wash was collected in a sterile container, plated onto blood and MacConkey agar, incubated at 37 degrees C, and examined for growth at 24 and 48 h. Personnel trained in accordance with approved procedures performed endoscope reprocessing.

RESULTS

A total of 312 surveillance cultures were performed between 1990 and 1999. Initially, three of 17 water bottles were found to be contaminated with Pseudomonas species. The bottles were sterilized daily; only sterile water was used and subsequent cultures were negative. Between 1992 and 1994, 15/129 (11.6%) cultures were positive; 14 (93%) were from duodenoscopes. From 1995 to 1997, 18/124 (14.5%) cultures were positive, but only six (33%) were from duodenoscopes. However, 10 (55.6%) positive cultures were obtained from therapeutic upper endoscopes, attributed to faulty mechanical cleaning by nonnursing personnel after emergent procedures. The reprocessing procedure was altered, with improvement. One duodenoscope was persistently culture positive and was found to have a damaged biopsy channel. There were no recognized iatrogenic infections associated with endoscopic procedures. Organisms cultured were commonly gram-negative rods.

CONCLUSIONS

The use of environmental endoscope culturing is a rapid, simple, inexpensive method to monitor effectiveness of standard reprocessing procedures. Disinfection is less effective with poor mechanical cleansing, and high-titer positivity is a marker for poor cleaning technique. Standard upper and lower scopes are commonly culture negative. Duodenoscopes, because of their inherent complexity, and other scopes used in emergent conditions require particular attention. Surveillance culture results can be used to identify patterns of poor technique, to reinforce proper procedure, and to modify clinical practice. No associated clinical illness was apparent during this study.

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.

A survey of reprocessing methods, residual viable bioburden, and soil levels in patient-ready endoscopic retrograde choliangiopancreatography duodenoscopes used in Canadian centers

OBJECTIVES

To obtain information about current reprocessing practices and to obtain samples from the biopsy channel to quantitate soil levels and bioburden in patient-ready flexible duodenoscopes used for endoscopic retrograde choliangiopancreatography (ERCP).

DESIGN

Participating centers were sent a questionnaire and a kit for on-site collection of samples from the biopsy channel of the duodenoscope.

SETTING

Thirty-seven hospitals from across Canada participated. The only criterion was that they currently used and reprocessed flexible duodenoscopes for ERCP procedures.

METHODS

The questionnaire obtained information on reprocessing practices. The kit included a detailed instruction booklet outlining sample collection and all of the tubes, sterile water, and brushes needed for it. Samples were collected on-site from all ERCP scopes in each center on Monday morning and shipped by overnight courier on ice to the research center. Each sample was assayed by routine microbiologic methods for total viable count and protein, blood, carbohydrate, and endotoxin levels.

RESULTS

Microbial overgrowth was present in 7% of 119 scope samples. Cleaning appeared to be reasonably well done in most of the centers, and 43% of the centers were in total compliance with basic national guidelines. The data from the scope samples indicated that there was significantly greater buildup of protein, carbohydrate, and endotoxin associated with ERCP scopes from centers using glutaraldehyde, compared with those using peracetic acid. Carbohydrate was the soil component detected most frequently and in the highest concentration in scope channels.

CONCLUSIONS

Although cleaning was generally well done, areas for improvement included ensuring the availability of written reprocessing protocols, immersion of scopes during manual cleaning, use of adequate fluid volume for rinsing, adequate drying of scopes prior to storage, and the separation of ERCP valves from scopes during storage.

Safety of technology: infection control standards in endoscopy

Transmission of infection related to gastrointestinal endoscopy continues to be a subject of much discussion. The principles of infection control during endoscopy are reviewed. Guidelines set forth by a number of gastrointestinal endoscopy associations have emphasized the need for meticulous cleaning of endoscopes immediately after use, followed by appropriate disinfection, rinsing and drying. Most, if not all, episodes of transmission of infection during endoscopy are associated with lapses in cleaning and disinfection protocols. The need for universal compliance with infection control standards, and for the development of strategies to achieve such compliance, is highlighted.

Evaluation of disinfectant efficacy against hepatitis C virus using a RT-PCR-based method

The methods traditionally used to evaluate the antiviral activity of antiseptics and disinfectants are based on cell cultures. However, such methods are not applicable to non-cultivable viruses such as hepatitis C (HCV). Therefore, in this case, virucidal activity is normally tested using surrogate viruses able to grow in cell culture. This paper describes a RT-PCR method for testing antiseptic/disinfectant activity against HCV, as a model for non-cultivable viruses. A chlorine-based agent used for skin and tissues, and a 2% glutaraldehyde solution used for endoscope disinfection, were the test materials. The results are discussed in the light of the use of these agents. The method is simple, fast and inexpensive, and could be used for tests on other viruses with minor modification.

A case-control study of transmission routes for GB virus C/hepatitis G virus in Swedish blood donors lacking markers for hepatitis C virus infection

BACKGROUND AND OBJECTIVES

The transmission routes for GB virus-C (GBV-C)/hepatitis G virus (HGV) in blood donors unexposed to hepatitis C virus (HCV) are unknown. We performed a case-control study of risk factors for GBV-C/HGV exposure in blood donors.

MATERIALS AND METHODS

After testing stored sera from 458 HCV-negative blood donors for GBV-C/HGV RNA and GBV-C/HGV E2 antibodies, 66 donors with GBV-C/HGV markers and 125 age- and gender-matched controls were interviewed regarding risk factors for viral transmission.

RESULTS

Exposure to GBV-C/HGV was strongly associated with previous treatment for a sexually transmitted disease (odds ratio [OR] 4.6; 95% confidence interval [CI] 2.2-9.8), with multiple sexual partners (OR 2.9; 95% CI 1.4-5.7) and with a past history of endoscopy (OR 7.0; 95% CI 3.0-16.4).

CONCLUSIONS

In blood donors with GBV-C/HGV markers, sexual contacts and medical procedures appear to be the main transmission routes.

Reprocessing of thermosensitive materials--efficacy against bacterial spores and viruses

To estimate process parameters for non-thermal methods of antimicrobial inactivation, the half-cycle method is very often used. However, the essential premise of this method of estimation, the independence of microbial inactivation kinetics from the microbial load, seems not to be true. Consequently, the attainment of the sterility assurance level as recommended by the pharmacopoeias by a process which has been validated using the half cycle method is not guaranteed. For the evaluation of such chemo-thermo disinfection processes, the quantification of remaining hepatitis B virus DNA (HBV-DNA) traces on the surface of instruments is a useful tool. An infection can be excluded if a decrease of the HBN3-DNA residues on the instruments below the minimum infective dose can be demonstrated. Using the signal amplification technique to detect HBV-DNA on instruments, the safety of an reprocessing procedures can be improved.

Pseudo-outbreak of Mycobacterium chelonae and Methylobacterium mesophilicum caused by contamination of an automated endoscopy washer

OBJECTIVE

To evaluate an unusual number of rapidly growing acid-fast bacilli, later identified as Mycobacterium chelonae, and pink bacteria, later identified as Methylobacterium mesophilicum, from fungal cultures obtained by bronchoscopy.

DESIGN

Outbreak investigation.

SETTING

An academic medical center performing approximately 500 bronchoscopies and 4,000 gastrointestinal endoscopies in 1998.

PATIENTS

Patients undergoing bronchoscopy July 21 to October 2, 1998.

METHODS

The infection control department reviewed patient charts and bronchoscopy logs; obtained cultures of source water, faucets, washers, unopened glutaraldehyde, glutaraldehyde from the washers, and endoscopes; observed endoscope and bronchoscope cleaning and disinfecting procedures; reviewed glutaraldehyde monitoring records; and sent M. chelonae isolates for DNA fingerprinting.

RESULTS

M. chelonae, M. mesophilicum, gram-negative bacteria, and various molds grew from endoscopes, automated washers, and glutaraldehyde from the washers but not from unopened glutaraldehyde. The endoscopy unit regularly monitored the pH of glutaraldehyde, and the logs contained no deficiencies. The above sources remained positive for the same organisms after a glutaraldehyde cleaning cycle of the automated washers. DNA finger-printing of the M. chelonae revealed that they were clonally related.

CONCLUSIONS

The automated washers were contaminated with a biofilm that rendered them resistant to decontamination. The washers then contaminated the endoscopes and bronchoscopes they were used to disinfect. Our institution purchased new endoscopes and a new paracetic acid sterilization system.

A new hydrogen peroxide--based medical-device detergent with germicidal properties: comparison with enzymatic cleaners

BACKGROUND

The objective of this study was to evaluate the efficacy of the cleaning and bacterial killing ability of a new non-enzyme-based formulation (killing detergent solution [KDS]) compared with commercially available enzymatic detergents that included Metrizyme (Metrex Research Division of Sybron Canada Ltd. Morrisburg, Ontario) and Gzyme (Germiphene Corp, Brantford, Ontario). KDS is a hydrogen peroxide-based detergent formulation that combines cleaning efficacy with the ability to kill microorganisms. The KDS formulation helps ensure the protection of the health care worker from infectious risk during the soaking and cleaning stages of medical device reprocessing and reduces the bioburden on devices before sterilization/disinfection.

METHODS

Test organisms that included Enterococcus faecalis, Salmonella choleraesuis, Staphylococcus aureus, and Pseudomonas aeruginosa were suspended in artificial test soil (ATS-B; patent submitted), inoculated at 10(6) colonyforming units per carrier and dried overnight before detergent exposure. The ATS-B mimics the blood, protein, carbohydrate, and endotoxin levels of patient-used medical devices. Plastic lumen carriers and a flexible colonoscope were used for surface and simulated-use testing, respectively.

RESULTS

The results for the microbial challenge dried onto polyvinyl chloride (PVC) carriers demonstrated that the ability of KDS to remove protein, blood, carbohydrate, and endotoxin from surface test carriers was as effective as the enzyme detergents that were evaluated. Furthermore, KDS was able to effect approximately a 5-Log(10) reduction in microbial loads with a 3-minute exposure at room temperature, whereas none of the other detergents were as effective. In simulated-use testing of a soiled colonoscope, KDS was significantly better at ensuring microbial killing compared with Gzyme and Metrizyme and was equivalent to the enzymatic detergents in cleaning ability.

CONCLUSIONS

In summary the KDS has excellent microbial-killing ability in 3-minute exposures at room temperature and cleans as well as the existing enzymatic detergent formulations that were tested.

Pitfalls in endoscope reprocessing: brushing of air and water channels is mandatory for high-level disinfection

BACKGROUND

Endoscopic transmission of pathogens has been reported. Guidelines have been formulated concerning the risk of infection via contaminated suction and accessory channels. Contamination of the other 2 channels for air and water has not been demonstrated. These channels were examined to clarify whether they require cleaning.

METHODS

Endoscopes used for examinations were divided into 2 groups. Group A endoscopes (n = 20) were brushed along the air and water channels. Group B endoscopes (n = 22) were not. After machine reprocessing, specimens were obtained for bacterial culture. The residual protein was measured in the 2 channels by using amido black 10B dye, and results were compared between the 2 groups.

RESULTS

With regard to the air channel, there were no contaminated endoscopes detected in either group. For the water channel, 1 endoscope in group B was positive whereas there were none positive in group A. With regard to quantification of residual protein, brushing diminished the level in both the air and the water channels.

CONCLUSION

The air and water channels can become contaminated. Brushing every channel is mandatory for high-level disinfection. A redesign of the fundamental structure of endoscopes is proposed.

Hepatitis C virus and oral disease: a critical review

Hepatitis C virus (HCV) infection is widespread with an estimated 3% of the world population being infected. Acute infection is usually mild but chronicity develops in as many as 70% of patients, of whom at least 20% will eventually develop cirrhosis. A further 1-4% of cirrhotic individuals will develop hepatocellular carcinoma. Infection with HCV may have effects on various organs other than the liver. HCV has been causally associated with a remarkable array of extrahepatic manifestations, some of which remain unproven. This review discusses the evidence implicating HCV in the aetiology of two important oral conditions, namely Sjögren's syndrome and lichen planus.