Mycobacteria and glutaraldehyde: is high-level disinfection of endoscopes possible?

Scanning Electron Microscopy Analysis and Energy Dispersion X-ray Microanalysis to Evaluate the Effects of Decontamination Chemicals and Heat Sterilization on Implant Surgical Drills: Zirconia vs. Steel

Background: Drills are an indispensable tool for dental implant surgery. Today, there are ceramic zirconium dioxide and metal alloy drills available. Osteotomy drills are critical instruments since they come in contact with blood and saliva. Furthermore, they are reusable and should be cleaned and sterilized between uses. Depending on the material, sterilizing agents and protocols can alter the surface and sharpness of implant drills. The hypothesis is that cleaning and sterilization procedures can affect the surface structure of the drills and consequently reduce their cutting efficiency. Methods: Eighteen zirconia ceramic drills and eighteen metal alloy drills were evaluated. Within the scope of this study, the drills were not used to prepare implant sites. They were immersed for 10 min in human blood taken from volunteer subjects and then separately exposed to 50 cycles of cleansing with 6% hydrogen peroxide, cold sterilization with glutaraldehyde 2%, and autoclave heat sterilization. Scanning Electron Microscopy (SEM) and energy dispersion X-ray (EDX) microanalysis were conducted before and after each cycle and was used to evaluate the drill surfaces for alterations. Results: After exposure to the cleansing agents used in this study, alterations were seen in the steel drills compared to zirconia. Conclusions: The chemical sterilization products used in this study cause corrosion of the metal drills and reduce their sharpness. It was observed that the cycles of steam sterilization did not affect any of the drills. Zirconia drill surfaces remained stable.

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.

Effectiveness of current disinfection procedures against biofilm on contaminated GI endoscopes

BACKGROUND AND AIMS

Attention to patient safety has increased recently due to outbreaks of nosocomial infections associated with GI endoscopy. The aim of this study was to evaluate current cleaning and disinfection procedures of endoscope channels with high bioburden and biofilm analysis, including the use of resistant mycobacteria associated with postsurgical infections in Brazil.

METHODS

Twenty-seven original endoscope channels were contaminated with organic soil containing 10(8) colony-forming units/mL of Pseudomonas aeruginosa, Staphylococcus aureus, or Mycobacterium abscessus subsp bolletii. Biofilms with the same microorganisms were developed on the inner surface of channels with the initial inoculum of 10(5) colony-forming units/mL. Channels were reprocessed following current protocol, and samples from cleaning and disinfection steps were analyzed by bioluminescence for adenosine triphosphate, cultures for viable microorganisms, and confocal microscopy.

RESULTS

After contamination, adenosine triphosphate levels increased dramatically, and high bacterial growth was observed in all cultures. After cleaning, adenosine triphosphate levels decreased to values comparable to precontamination levels, and bacterial growth was demonstrated in 5 of 27 catheters, 2 with P aeruginosa and 3 with M abscessus. With regard to induced biofilm, a remarkable reduction occurred after cleaning, but significant microbial growth inhibition occurred only after disinfection. Nevertheless, viable microorganisms within the biofilm were still detected by confocal microscopy, more so with glutaraldehyde than with peracetic acid or O-phataladehyde.

CONCLUSION

After the complete disinfection procedure, viable microorganisms could still be detected within the biofilm on endoscope channels. Prevention of biofilm development within endoscope channels should be a priority in disinfection procedures, particularly for ERCP and EUS.

Transmission of infection by flexible gastrointestinal endoscopy and bronchoscopy

Flexible endoscopy is a widely used diagnostic and therapeutic procedure. Contaminated endoscopes are the medical devices frequently associated with outbreaks of health care-associated infections. Accurate reprocessing of flexible endoscopes involves cleaning and high-level disinfection followed by rinsing and drying before storage. Most contemporary flexible endoscopes cannot be heat sterilized and are designed with multiple channels, which are difficult to clean and disinfect. The ability of bacteria to form biofilms on the inner channel surfaces can contribute to failure of the decontamination process. Implementation of microbiological surveillance of endoscope reprocessing is appropriate to detect early colonization and biofilm formation in the endoscope and to prevent contamination and infection in patients after endoscopic procedures. This review presents an overview of the infections and cross-contaminations related to flexible gastrointestinal endoscopy and bronchoscopy and illustrates the impact of biofilm on endoscope reprocessing and postendoscopic infection.

Post percutaneous nephrolithotripsy nephrostomy site tuberculosis: A report of six cases

With the increase in endoscopic surgery, there is a growing concern about the effectiveness of sterilizing reusable equipment by immersion in 2% glutaraldehyde. Although reports of port site tuberculosis (post laparoscopy) are there in the literature, those of nephrostomy site post percutaneous nephrolithotripsy are not available. We describe the clinical features and treatment of six patients who presented with biopsy-proven skin tuberculosis at the nephrostomy-site for non-healing wound.

A new peroxide-based flexible endoscope-compatible high-level disinfectant

Semicritical medical devices such as flexible endoscopes require high-level disinfection between each use, and glutaraldehyde is often used for this purpose because of its favorable materials compatibility. However, workplace safety and the relatively slow microbicidal activity of such formulations remain a concern. Although recently introduced substitutes based on 0.55% ortho-phthaldehyde (OPA), 7% to 14% hydrogen peroxide, and 0.1% to 0.3% peracids are considered less toxic than glutaraldehyde, OPA can be a potential respiratory sensitizer, and the materials compatibility profile of peroxide/peracids at effective concentrations remains an issue. This study describes a high-level disinfectant/sterilant based on 2% accelerated hydrogen peroxide (AHP). It is a blend of stabilized hydrogen peroxide with safe inerts, which act in synergy, and has a 14-day reuse, 5-minute high-level disinfection, and 6-hour sterilization claim at room temperature. Extensive testing of this formulation using nationally and internationally accepted protocols has found it to be a fast-acting and broad-spectrum microbicide in addition to being biodegradable, virtually nontoxic, and free from volatile organic compounds and alkyl phenol ethoxylates. In addition, materials compatibility testing has proven it to be compatible with flexible endoscopes. Therefore, this new chemistry represents a significant advancement in the design of safer and faster acting, high-level disinfectants.

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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The influence of endoscopic procedures upon the contamination of Helicobacter pylori cultures

BACKGROUND

Among the various diagnostic methods for the detection of Helicobacter pylori infection, histological examination and microbiological processing of gastric biopsy samples are assumed to be the gold standard techniques.

AIMS

Since H. pylori culture can be affected by the presence of non-H. pylori bacteria, we evaluated the efficacy of endoscope disinfection and the influence of endoscopic procedures on culture contamination.

PATIENTS AND METHODS

The procedures used during the first two routine endoscopies were evaluated during 28 consecutive days. Endoscopy room, forceps and endoscopic channel were analyzed before and after the beginning of normal procedures. After disinfection, a biopsy simulation was performed to verify the gastric bacteria.

RESULTS

Endoscope disinfection removed all organisms from forceps and endoscopic channel with 100% efficacy. The most frequent non-H. pylori bacteria detected were Streptococcus bovis, Enterobacter hormaechei, and Staphylococcus aureus. The sensibility of the H. pylori culture was affected by the presence of non-H. pylori bacteria.

CONCLUSION

The risk of transmission of microorganisms was not detectable when sterilized biopsy forceps and stringent disinfection standards were employed. Whilst S. bovis and E. hormaechei may be common in gastric microbial flora, the presence of P. aeruginosa and S. aureus indicated that the manipulation of biopsies could be responsible for culture contamination with these bacteria.

Reprocessing endoscopes: United States perspective

Endoscopes are used frequently for the diagnosis and therapy of medical disorders. For example, greater than 10000000 gastrointestinal endoscopic procedures are performed each year in the United States. Failure to employ appropriate cleaning and disinfection/sterilization of endoscopes has been responsible for multiple nosocomial outbreaks and serious, sometimes life-threatening, infections. Flexible endoscopes, by virtue of the site of use, have a high bioburden of microorganisms after use. The bioburden found on flexible gastrointestinal endoscopes following use has ranged from 10(5) to 10(10)CFU/ml, with the highest levels being found in the suction channels. Cleaning dramatically reduces the bioburden on endoscopes. Several investigators have shown a mean log(10) reduction factor of 4 (99.99%) in the microbial contaminants with cleaning alone. Cleaning should be done promptly following each use of an endoscope to prevent drying of secretions, allow removal of organic material, and decrease the number of microbial pathogens. Because the endoscope comes into intimate contact with mucous membranes, high-level disinfection is the reprocessing standard after each patient use. High-level disinfection refers to the use of a disinfectant (e.g., FDA-cleared chemical sterilant or high-level disinfectant) that inactivates all microorganisms (i.e., bacteria, viruses, fungi, mycobacteria) but not high levels of bacterial spores. The disinfection process requires immersion of the endoscope in the high-level disinfectant and ensuring all channels are perfused for the approved contact time (e.g., for ortho-phthaladehyde this is 12 min in the US). Following disinfection, the endoscope and channels are rinsed with sterile water, filtered water, or tapwater. The channels are then flushed with alcohol and dried using forced air. The endoscope should be stored in a manner that prevents recontamination. A protocol that describes the meticulous manual cleaning process, the appropriate training and evaluation of the reprocessing personnel, and a quality assurance program for endoscopes should be adopted and enforced by each unit performing endoscopic reprocessing.

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.

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.

Non-inflatable sterile sheath for introduction of the flexible nasopharyngolaryngoscope

Since the inception of the flexible nasopharyngolaryngoscope, sterility has been a primary concern. The increased incidence of hepatitis, tuberculosis, and acquired immunodeficiency syndrome has raised the fear of cross-contamination. Sterilization requires the use of ethylene oxide, which is economically disadvantageous, forcing most practitioners to disinfect rather than sterilize their nasopharyngolaryngoscopes. A presterilized, disposable sheath was designed in 1993. The system was cumbersome, because it required an air pump. Thus, it was not adopted by the majority of physicians. As a result, the manufacturer developed a new system, which I evaluated. It is cost-effective, smoother-surfaced, 70% thinner-walled, and much simpler to use. The disposable, single-use sheath is sterile, with no need for a pump or any additional device, and can be used anywhere at any time. I believe it will become the standard method for sterile introduction of the nasopharyngolaryngoscope.

Efficacy of high-level disinfectants for reprocessing GI endoscopes in simulated-use testing

BACKGROUND

There has been recent public concern regarding the adequacy of current practices for flexible endoscope reprocessing. High-level disinfection is defined by the Food and Drug Administration (FDA) as a minimum of 6-log reduction of mycobacteria under a worst-case scenario. Several agents are currently approved by the FDA, but published data on their relative efficacies against mycobacteria are lacking. The objective of this study was to determine the efficacy of these agents for high-level disinfection.

METHODS

In simulated-use testing, video endoscopes (5 colonoscopes and 5 duodenoscopes) were each inoculated with 9.0 x 10(7) colony-forming units of Mycobacterium chelonae. Cleaning was performed by using a standardized protocol. Each endoscope was then subjected to chemical disinfection with Cidex (2.0% glutaraldehyde) at 20 degrees C for 20 minutes, Sporox (7.5% hydrogen peroxide) at 20 degrees for 30 minutes, and Steris 20 (0.2% peracetic acid) at 50 degrees C to 56 degrees C for 12 minutes using the Steris System 1 processor. Although not FDA-approved, tests were also conducted by using 70% isopropyl alcohol at 20 degrees C for 20 minutes. These results were compared with disinfection with ethylene oxide gas. All channels were sampled for M chelonae before and after manual cleaning and after disinfection.

RESULTS

Cleaning alone resulted in an average log reduction of 3. Cidex, Sporox, Steris 20, ethylene oxide gas, and isopropyl alcohol, in combination with manual cleaning, each achieved a 6-log or greater reduction of the mycobacterial inoculum. No organisms were recovered from any channel after reprocessing with ethylene oxide and Steris 20.

CONCLUSIONS

Commercially available high-level disinfectants are equally efficacious for reprocessing flexible GI endoscopes when used in conjunction with cleaning and in accordance with recommended guidelines.

Endoscope washers--a protocol for their use

A protocol for the disinfection of gastroduodenoscopes, retrograde cholangiopancreatography endoscopes and colonoscopes using endoscope washers is described. The process recommends initial manual washing with a disinfectant containing didecyldimethylammonium chloride, surfactants and enzymes, a second washing in the endoscope washer using a detergent associated with a bacteriostatic, fungistatic substance (benzoisothiazolone) and finally the use of a 2% glutaraldehyde product buffered at pH6. After treatment with 2% Steranios added to the washer, less than 1 micro-organism/ml liquid was found in the following units: 83% of the colonoscopes, 83% of the oesophagogastroduodenoscopes, 83% of the main channels of the retrograde cholangiopancreatography endoscopes and 75% of the auxiliary channels of the latter instruments. In 14% of the colonoscopes, 42% of the gastroduodenoscopes, 42% of the main and 50% of auxiliary channels in the retrograde cholangiopancreatography endoscopes there were no signs of microbial growth in the wash liquid. The results obtained indicated that this protocol allowed adequate disinfection of the endoscope channels, structurally the most difficult part of the instrument to disinfect. Emphasis is given to the degree by which instrument contamination can increase during overnight storage, suggesting that endoscopes need to be submitted to further disinfection after overnight storage. Moreover, the water flowing into the washers can also cause instrument recontamination, particularly during the final rinses. Therefore, to better safeguard the health of patients undergoing endoscopy, special care must be taken to maintain the filters and disinfect the washers themselves, no matter how effective the disinfection protocol used may be.

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.

Efficacy of conventional endoscopic disinfection and sterilization methods against Helicobacter pylori contamination

BACKGROUND

Iatrogenic transmission of Helicobacter pylori via contaminated endoscopic devices is well documented. Despite the prevalence of this infectious agent, few controlled studies have investigated the major factors that impact on reprocessing of endoscopes contaminated with H. pylori.

MATERIALS AND METHODS

An endoscope (Pentax) was contaminated with 108 cfu/ml of H. pylori in 5% bovine calf serum as standardized inoculum. The endoscope then was passed through one of eight arms (five repetitions per arm = 40 total runs), as follows: 1, recovery control (no cleaning or disinfection); 2, manual cleaning alone; 3-5, manual precleaning followed by either 10-, 20-, or 45-minute exposure to 2% glutaraldehyde and ethanol (ETOH) drying; 6, manual cleaning followed by automated reprocessing by STERIS System; 7 and 8, automated reprocessing by STERIS with and without active peracetic acid sterilant (wash-off control). Suction-biopsy channels and air-water channels were harvested for microbiological culture.

RESULTS

Control runs recovered more than 1 x 106 cfu per site, confirming the viability of the test organism and the adequacy of the biological burden for challenge. When instruments underwent manual cleaning alone (without subsequent disinfection), test organisms remained in 40% of runs at the air-water site. Manual cleaning followed by 10-, 20-, or 45-minute glutaraldehyde exposure and ETOH drying removed all test organisms from all sites in all runs (i.e., 100% disinfection). The automated STERIS system with or without active peracetic acid sterilant also removed all test organisms from all sites in all runs, as did manual cleaning followed by STERIS use.

CONCLUSION

Manual cleaning alone does not effectively remove H. pylori from an endoscope. Current joint association recommendations for minimal disinfection (manual cleaning followed by at least 20 minutes of immersion in glutaraldehyde and ETOH drying) are effective in preventing cross-transmission of H. pylori. Reprocessing using the automated STERIS system according to manufacturer's recommendations also is highly effective in sterilizing endoscopes contaminated with H. pylori.

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

BACKGROUND

Adequate disinfection of endoscopes is essential to prevent environmental and patient-to-patient transmission of infectious agents, but data from controlled studies are limited. Moreover, there is controversy regarding current guidelines for disinfection. We compared the antimicrobial efficacy of several endoscopic disinfection procedures controlling for multiple factors that affect reprocessing.

METHODS

A colonoscope was contaminated with 10(8) CFU/mL of Enterococcus faecalis as a standardized inoculum. The colonoscope was passed through 1 of 16 study arms (5 reps/arm for a total of 80 runs) that were controlled for all possible combinations of the following variables: manual precleaning; 10-, 20-, or 45-minute glutaraldehyde exposure; air or ethanol drying; or automated reprocessing with peracetic acid (liquid sterilization system). Suction accessory channels and air-water channels were harvested for microbiologic culture.

RESULTS

Control runs (no cleaning or disinfection) recovered more than 5 x 10(7) CFU/mL from each sampling site. When each processing variable was isolated independent of other variables, the benefits of manual precleaning, longer soak times, and ethanol drying were apparent. When factors were combined, manual precleaning followed by 20- and 45-minute glutaraldehyde exposure and ethanol drying removed all test organisms, as did processing with the liquid sterilization system.

CONCLUSION

Although the initial cost is higher, the automated liquid sterilization system provides effective sterilization and minimizes worker exposure. In units where chemical disinfection is used, our results suggest that manual precleaning followed by at least 20-minute glutaraldehyde exposure and ethanol rinse drying are sufficient to achieve complete disinfection.

The efficacy of three common hospital liquid germicides to inactivate Cryptosporidium parvum oocysts

We evaluated three commonly used hospital disinfectants against three concentrations of Cryptosporidium parvum oocysts (1.5 x 10(6), 1.5 x 10(5), 1.5 x 10(4)). A 10% phenol product, a 10% povidone-iodine product and a 2.5% glutaraldehyde product were tested against Cryptosporidium parvum oocysts without organic load. In-vitro excystation was used to determine viability and a cell culture assay was used to determine infectivity of germicide-treated oocysts. A 2.5% glutaraldehyde product was the most effective in halting excystation of sporozoites and infection in cell monolayers. However, this occurred only at the longest exposure time of 10 h and with the lowest concentration of oocysts (1.5 x 10(4)). The 10% phenol product and the 10% povidone-iodine product also decreased excystation, but were unable to halt infection. Although the ability of C. parvum to with-stand chemical treatment is well known, the ability of oocysts to remain viable and infectious after a 10 h treatment in glutaraldehyde is cause for concern. Endoscopic equipment that may come into contact with these organisms cannot be immersed into glutaraldehyde for this length of time due to its corrosive nature. Thus, the results of this research are cause for concern in hospital disinfection units.

High-level disinfection of gastrointestinal endoscopes: are current guidelines adequate?

OBJECTIVE

For a germicide to obtain a high level disinfection (HLD) claim, FDA requires demonstration of a 6-log reduction of mycobacterial inoculum under worst case conditions. The purpose of this study was to assess the adequacy of current guidelines for high level disinfection of GI endoscopes using alkaline glutaraldehyde in simulated-use testing.

METHODS

Various gastrointestinal endoscopes were contaminated with Mycobacterium chelonae in 46 experiments. Quantitative cultures were obtained from each endoscope channel separately after each step: inoculation, standardized manual cleaning, immersion in 2% glutaraldehyde (Cidex) for 10, 20, or 45 min at room temperature, 70% isopropanol rinse, and drying.

RESULTS

Manual cleaning alone achieved a 4-log reduction. After 10 min of glutaraldehyde exposure, but before alcohol rinse, two of 10 experiments failed to achieve a 6-log reduction. However, after alcohol rinse, all 10 experiments achieved HLD. After 20 min of glutaraldehyde exposure, but before alcohol rinse, one of 18 experiments failed to achieve a 6-log reduction. After alcohol rinse, all 18 experiments achieved HLD. After 45 min of glutaraldehyde exposure, but before alcohol rinse, one of 18 experiments failed to achieve a 6-log reduction. After alcohol rinse, all 18 experiments achieved HLD. Thus, if the entire reprocessing protocol including manual cleaning, glutaraldehyde exposure, alcohol rinse, and drying was taken into account, the required 6-log reduction of mycobacteria was achieved with a minimum of 10 min of glutaraldehyde exposure at room temperature.

CONCLUSIONS

Current guidelines for high level disinfection using glutaraldehyde are appropriate. Alcohol rinse is a valuable adjunctive step for drying and for its bactericidal effects.

The mycobactericidal efficacy of ortho-phthalaldehyde and the comparative resistances of Mycobacterium bovis, Mycobacterium terrae, and Mycobacterium chelonae

OBJECTIVES

To assess the mycobactericidal efficacy of an agent relatively new to disinfection, ortho-phthalaldehyde (OPA) and to compare the resistances of three Mycobacterium species. Mycobacterium bovis (strain BCG) was compared with Mycobacterium chelonae and Mycobacterium terrae to investigate the feasibility of using either of the latter two species in tuberculocidal testing. M. chelonae (a rapid grower) and M. terrae (an intermediate grower) both grow faster and are less virulent than M. bovis (a slow grower).

DESIGN

The quantitative suspension protocol specified by the Environmental Protection Agency (EPA), the Tuberculocidal Activity Test Method (EPA test), was used throughout this study. Standard suspensions of all three species were prepared in a similar manner. Two suspensions of M. bovis, created in different laboratories, were used. These were tested against two concentrations of alkaline glutaraldehyde to provide reference data. Two concentrations of OPA were evaluated against all mycobacterial test suspensions. Four replicates of each organism-disinfectant combination were performed.

RESULTS

Results were assessed by analysis of variance. M. terrae was significantly more resistant to 0.05% OPA than either M. bovis or M. chelonae. At 0.21% OPA, M. terrae was slightly more susceptible than one test suspension of M. bovis, but not significantly different from the other. M. chelonae was significantly less resistant than the other species at both OPA concentrations. At their respective minimum effective concentration, OPA achieved a 6-log10 reduction of M. bovis in nearly one sixth the time required by glutaraldehyde (5.5 minutes vs. 32 minutes).

CONCLUSIONS

These data, along with other recent studies, lend support to the idea that M. terrae may be a suitable test organism for use in the tuberculocidal efficacy testing of disinfectants. They also confirm the relatively rapid tuberculocidal activity of OPA.

Microbial bioburden in endoscope reprocessing and an in-use evaluation of the high-level disinfection capabilities of Cidex PA

Most endoscopy clinics use 2% glutaraldehyde as a high-level disinfectant for reprocessing flexible endoscopes. However, even with contact times greater than 30 minutes, survival of organisms has been documented. We compared the high-level disinfection capabilities of glutaraldehyde (45-minute immersion) with a new peracetic acid germicide (20- to 25-minute immersion). Channels, valve housings, and outer sheaths were sampled to quantify bioburden levels after a patient procedure, after manual cleaning, and after disinfection. Total mean bioburden after clinical use was greater than 6 log10 colony-forming units (CFU). Manual cleaning reduced the bioburden by means of 4.7 log10 CFU (gastroscopes) and 6.2 log10 CFU (colonoscopes). High-level disinfection with the new product was achieved in five of six (product stressed by EPA Reuse Test) and 7 of 10 (product stressed by dilution and organic load) successfully disinfected endoscopes, whereas glutaraldehyde achieved it in 4 of 10 (product stressed by dilution and organic load). We conclude that the new peracetic acid product (20- and 25-minute contact time) is at least as effective as glutaraldehyde (45-minute contact time) for reducing the bioburden of vegetative aerobic organisms in endoscopes.

Efficacy of various disinfectants in killing a resistant strain of Pseudomonas aeruginosa by comparing zones of inhibition: implications for endoscopic equipment reprocessing

OBJECTIVE

Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably achieved using glutaraldehyde at room temperature. In our laboratory, we have isolated a strain of Pseudomonas aeruginosa that is resistant to disinfection with glutaraldehyde. We compared the bactericidal activity of various disinfectants against this organism.

METHODS

One hundred microliters of an overnight culture of this organism was spread onto blood agar plates. Twenty microliters of a disinfectant was placed on a sterile 7-mm filter paper, placed on the blood agar plate, and incubated overnight at 37 degrees C to determine the zone of inhibition for each disinfectant tested. Disinfectants included Cidex, Dispatch, Virahol, OMNI II, Lysol, IodoFive, Lysol I.C. Spray, and Chlorox. The zone of inhibition (i.e., clearing) roughly correlates with the bactericidal strength of the disinfectant.

RESULTS

Compared with the glutaraldehyde-containing solution Cidex, the alcohol-containing disinfectants Lysol I.C. Spray and Virahol had the largest mean zones of inhibition (11.33 vs 20.60 and 20.55 mm; p = 0.0001). The hypochlorite compounds Chlorox (1:10 dilution) and Dispatch had mean zones of inhibition similar to that of Cidex (11.08 and 11.25 mm vs 11.33 mm; p = not significant). The phenolic compounds OMNI II and Lysol had mean zones of inhibition smaller than that of Cidex (10.50 and 10.35 mm vs 11.33 mm; p < 0.006), and the phosphoric acid and iodine-containing IodoFive had the smallest mean zone of inhibition (9.70 vs 11.33 mm; p = 0.0001).

CONCLUSIONS

The alcohol-containing disinfectants had the largest zones of inhibition against resistant P. aeruginosa. These compounds may be more effective than glutaraldehyde for endoscopic equipment reprocessing.

Risk of contamination of sterile biopsy forceps in disinfected endoscopes

BACKGROUND

Previous studies have shown that pathogens may persist within bacterial biofilms in endoscope accessory channels despite high-level disinfection. Breaching the gastrointestinal mucosa with biopsy forceps contaminated at time of passage has the potential to cause cross-infection between patients.

METHODS

We studied contamination risk of sterilized biopsy forceps passed through endoscopes after high-level disinfection. For each trial, five video colonoscopes, duodenoscopes, and gastroscopes were used. All endoscopes had been previously processed and stored for 10 or more hours. Sterile biopsy forceps were inserted and retrieved followed by vortexing the tips in 15 mL of soy broth. Under a laminar flow hood, the broth was filtered through a 0.2 microm millipore membrane and plated. Because of minimal bacterial growth resulting from the above, soy broth (> 20 mL) was flushed through two video colonoscopes, duodenoscopes, and gastroscopes on two occasions and collected. The effluent was plated using a sample of 0.1 mL dilution. The remaining suspension was passed through a millipore filter, and the filter was cultured. All cultures were incubated more than 48 hours.

RESULTS

Biopsy forceps underwent a total of 24 anaerobic and 75 aerobic cultures. Microbacterial growth occurred on 17 plates: 7 from gastroscopes, 5 from colonoscopes, and 5 from duodenoscopes. Fifteen plates grew staphylococcus for a total of 21 colonies, 1 plate grew 1 colony of propionibacter, 2 plates grew diphtheroids for a total of 4 colonies, and 1 plate grew a single colony of lactobacillus. Cultures from soy broth flushed through the various endoscopes grew on 5 plates: 3 from gastroscopes and 2 from duodenoscopes grew a total of 8 colonies of staphylococcus.

CONCLUSIONS

With proper cleaning technique, a 20-minute soak in 2% glutaraldehyde is effective in disinfecting endoscopes. Although current procedures for endoscope disinfection remain imperfect, we found that in this clinical setting, infection of pathogenic gastrointestinal flora is unlikely when using sterile biopsy forceps.

Efficiency and productivity of a sheathed fiberoptic sigmoidoscope compared with a conventional sigmoidoscope

PURPOSE

The aim of this study was to measure and compare time and productivity between a new sheathed flexible sigmoidoscope and a traditional fiberoptic flexible sigmoidoscope relative to labor and cost analysis.

METHODS

Two flexible sigmoidoscopes, the Vision Sciences sigmoidoscope using a protective sheath covering requiring removal and replacement between procedures and a conventional flexible sigmoidoscope requiring meticulous cleaning using a washer and high-level disinfection, were compared. Sigmoidoscope preparation was defined as the average time between the procedures (reprocessing, start to finish) and was measured by an independent nonmedical timekeeper JG). The parameter recorded was scope reprocessing time.

RESULTS

Ten procedures were performed using the sheathed flexible sigmoidoscope system compared with nine using a conventional sigmoidoscope. Scope performance and endoscopic visualization for both systems were comparable. The average reprocessing time was 46.8 minutes for the conventional sigmoidoscope vs. 4.9 minutes for the sheathed sigmoidoscope (P < 0.0001). The average time saved was 9.5 times greater with the sheathed flexible sigmoidoscope system than with the conventional sigmoidoscope.

CONCLUSION

The almost tenfold difference in the time saved using the sheathed flexible sigmoidoscope system represents increased productivity and potentially decreased overall labor cost. By reducing endoscope turnover time, this new sheathed system can reduce or even eliminate the need for backup endoscopes and endoscope washers and potentially allow better use of nursing staff.

In vitro evaluation of wire integrity and ability to reprocess single-use sphincterotomes

BACKGROUND

Sphincterotomes are currently marketed as one-time-use items and constitute considerable cumulative expense in a busy endoscopy unit. It is uncertain whether these accessories can be safely reprocessed without loss of form and function.

METHODS

We studied disposable sphincterotomes (five 5F, five 6F) in vitro as to their durability, electrical integrity, and ability to be adequately cleaned both manually and with ethylene oxide after contamination with 10(5) to 10(6) Mycobacterium chelonei.

RESULTS

Seven of the 10 sphincterotomes withstood the rigors of reuse; three 6F sphincterotomes developed wire fracture between four and eight uses. Electrical integrity, as measured by an electrosurgical analyzer, remained intact up to time of breakage in all sphincterotomes. Manual cleaning followed by glutaraldehyde soak resulted in residual mycobacterial colonies in five 6F sphincterotomes and a single 5F sphincterotome. No instrument had residual organisms cultured following manual cleaning and ethylene oxide sterilization.

CONCLUSIONS

The authors conclude that one-time-use sphincterotomes have the potential for safe reuse.

Evaluation of per-procedure equipment costs in an outpatient endoscopy center

BACKGROUND

As disposable endoscopes become available, we need baseline costs associated with reusable instruments to make financially intelligent choices. Accordingly, we analyzed the per-use cost of several types of gastrointestinal endoscopes at our institution.

METHODS

Records of 44 gastrointestinal endoscopes were analyzed. Data defined included purchase price, repair and cleaning expense (labor and materials), and number of uses. The labor cost per-use associated with endoscope cleaning was estimated by taking an average time required to clean an endoscope multiplied by the technician's salary.

RESULTS

The average number of years of endoscope use varied from 4.6 to 6.9 years contingent on the type of endoscope. For flexible sigmoidoscopes, the average total cost per use was $8.35, and for colonoscopes the cost was $21.81. For gastroscopes and diagnostic and therapeutic duodenoscopes, costs were $20.99, $49.15, and $45.16, respectively.

CONCLUSIONS

(1) Excluding costs associated with the procedure itself (admit-recovery, drugs, disposable equipment, and procedural personnel), total peruse scope cost ranged from a low of $8.35 for the flexible sigmoidoscope to $49.15 for the diagnostic duodenoscope. (2) The most important variables associated with per-use endoscope cost included number of uses, initial purchase price, and repair costs. (3) Techniques such as the above can be used to define per-procedure costs for a particular practitioner or institution.