Disinfection of endoscopes: review of new chemical sterilants used for high-level disinfection

Effects of disinfectants on physical properties of denture base resins: A systematic review and meta-analysis

STATEMENT OF PROBLEM

The disinfection of removable dental prostheses and orthodontic appliances is essential to preventing transmission of pathogens. However, whether different disinfection solutions and durations affect the physical properties of denture base resins is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to statistically analyze the influence of disinfectants on the physical properties of denture base resins.

MATERIAL AND METHODS

A systematic search in Medline, Embase, PubMed, and Cochrane Library databases was conducted to evaluate the effects of chemical disinfection on the physical properties of denture base resins such as surface morphology, roughness, hardness, and flexural strength. Of 1909 studies, 44 studies were included in the systematic review and 41 in the meta-analysis. Heterogeneity was analyzed by using I2 statistics. The influence of different disinfection solutions and durations on the physical properties was further analyzed, and the risk of bias evaluated. Statistical analyses were performed by using the RevMan 5.4 software program with the standardized mean differences (SMDs) and 95% confidence intervals (CIs).

RESULTS

Of the 44 included studies, 40 studies were assessed as having a low risk of bias, and 4 had an unclear risk of bias. Meta-analysis results showed that compared with the control, disinfection could not significantly affect surface roughness and hardness within 60 minutes of immersion in disinfectant solutions or flexural strength within 30 minutes (roughness: P=.79, I2=0%; flexural strength: P=.08, I2=0%; hardness: P=.05, I2=19%). In addition, the physical properties were not significantly affected when glutaraldehyde, chlorhexidine, and peracetic acid were repeatedly used for more than 30 minutes.

CONCLUSIONS

Most of the disinfectants did not reduce the physical properties of denture base resin within 30 minutes of immersion. Glutaraldehyde, chlorhexidine, and peracetic acid are recommended if longer immersion or repeated disinfection is required.

The Evolution of Spinal Endoscopy: Design and Image Analysis of a Single-Use Digital Endoscope Versus Traditional Optic Endoscope

Spinal endoscopy has evolved significantly since its inception, offering minimally invasive solutions for various spinal pathologies. This study introduces a promising innovation in spinal endoscopy-a single-use digital endoscope designed to overcome the drawbacks of traditional optic endoscopes. Traditional endoscopes, despite their utility, present challenges such as fragility, complex disinfection processes, weight issues, and susceptibility to mechanical malfunctions. The digital endoscope, with its disposable nature, lighter weight, and improved image quality, aims to enhance surgical procedures and patient safety. The digital endoscope system comprises a 30-degree 1000 × 1000 pixel resolution camera sensor with a 4.3 mm working channel, and LED light sources replacing optical fibers. The all-in-one touch screen tablet serves as the host computer, providing portability and simplified operation. Image comparisons between the digital and optic endoscopes revealed advantages in the form of increased field of view, lesser distortion, greater close-range resolution, and enhanced luminance. The single-use digital endoscope demonstrates great potential for revolutionizing spine endoscopic surgeries, offering convenience, safety, and superior imaging capabilities compared to traditional optic endoscopes.

In Vitro Microevolution and Co-Selection Assessment of Florfenicol Impact on Escherichia coli Resistance Development

The issue of antimicrobial resistance is becoming an increasingly serious challenge in both human and veterinary medicine. Prudent antimicrobial use in veterinary medicine is warranted and supported by international guidelines, with the Antimicrobial Advice Ad Hoc Expert Group (AMEG) placing particular emphasis on the critically important group B antimicrobials. These antimicrobials are commonly employed, especially in the poultry and swine industry. The impact of florfenicol, a veterinary antibiotic, was studied on the resistance development of Escherichia coli. The aim of the study was to investigate the effect of the use of florfenicol on the development of phenotypic and genomic resistances, not only to the drug itself but also to other drugs. The minimum inhibitory concentrations (MICs) of the antibiotics were investigated at 1×, 10×, 100× and 1000× concentrations using the adapted Microbial Evolution and Growth Arena (MEGA-plate) method. The results demonstrate that florfenicol can select for resistance to fluoroquinolone antibiotics (167× MIC value increase) and cephalosporins (67× MIC value increase). A total of 44 antimicrobial resistance genes were identified, the majority of which were consistent across the samples. Chromosomal point mutations, including alterations in resistance-associated and regulatory genes (acrB, acrR, emrR and robA), are thought to trigger multiple drug efflux pump activations, leading to phenotypically increased resistance. The study underscores the impact of florfenicol and its role in the development of antimicrobial resistance, particularly concerning fluoroquinolone antibiotics and cephalosporins. This study is the first to report florfenicol's dose-dependent enhancement of other antibiotics' MICs, linked to mutations in SOS-box genes (mdtABC-tolC, emrAB-tolC and acrAB-tolC) and increased multidrug efflux pump genes. Mutations in the regulatory genes acrR, emrR and rpbA support the possibility of increased gene expression. The results are crucial for understanding antimicrobial resistance and its development, highlighting the promising potential of in vitro evolutionary and coselection studies for future research.

Responses of Salmonella biofilms to oxidizing biocides: Evidence of spatial clustering

The spatial organization of biofilm bacterial communities can be influenced by several factors, including growth conditions and challenge with antimicrobials. Differential survival of clusters of cells within biofilms has been observed. In this work, we present a variety of methods to identify, quantify and statistically analyse clusters of live cells from images of two Salmonella strains with differential biofilm forming capacity exposed to three oxidizing biocides. With a support vector machine approach, we showed spatial separation between the two strains, and, using statistical testing and high-performance computing (HPC), we determined conditions which possess an inherent cluster structure. Our results indicate that there is a relationship between biocide potency and inherent biofilm formation capacity with the tendency to select for spatial clusters of survivors. There was no relationship between positions of clusters of live or dead cells within stressed biofilms. This work identifies an approach to robustly quantify clusters of physiologically distinct cells within biofilms and suggests work to understand how clusters form and survive is needed. SIGNIFICANCE STATEMENT: Control of biofilm growth remains a major challenge and there is considerable uncertainty about how bacteria respond to disinfection within a biofilm and how clustering of cells impacts survival. We have developed a methodological approach to identify and statistically analyse clusters of surviving cells in biofilms after biocide challenge. This approach can be used to understand bacterial behaviour within biofilms under stress and is widely applicable.

Assessing nonsexual transmission of the human papillomavirus (HPV): Do our current cleaning methods work?

Human papillomavirus (HPV) is thought to be sexually transmitted; however, there have been a few studies investigating a possible iatrogenic source of infection. Therefore, it is important to assess the cleaning methods of reusable medical devices. This study assessed whether cleaning methods of flexible endoscopes in an otolaryngology clinic are effective against HPV. There were 24 patients with a history of head and neck cancer in the study; however, two outliers were excluded. Nine patients were confirmed to have HPV-associated cancer. PCR was used to measure and quantify the viral genomes of samples collected before and after cleaning. After cleaning, few HPV+ samples had endoscopes with less DNA than before cleaning. Additionally, for several patients with non-HPV-associated head and neck cancer, PCR showed more DNA after cleaning than before cleaning, suggesting residual HPV DNA within the cleaning solution. There was no significant difference (p > 0.05) between pre- and post-cleaning in both cohorts. Current cleaning methods of reusable endoscopes may not be effective in completely removing viral DNA.

On the Disinfection of Electrochemical Aptamer-Based Sensors

Electrochemical aptamer-based (EAB) sensors encompass the only biosensor approach yet reported that is simultaneously: (1) independent of the chemical or enzymatic reactivity of its target, rendering it general; (2) continuous and real-time; and (3) selective enough to deploy in situ in the living body. Consistent with this, in vivo EAB sensors supporting the seconds-resolved, real-time measurement of multiple drugs and metabolites have been reported, suggesting the approach may prove of value in biomedical research and the diagnosis, treatment, and monitoring of disease. However, to apply these devices in long-duration animal models, much less in human patients, requires that they be free of any significant pathogen load. Thus motivated, here we have characterized the compatibility of EAB sensors with standard sterilization and high-level disinfection techniques. Doing so, we find that, while many lead to significant sensor degradation, treatment with CIDEX OPA (0.55% ortho-phthalaldehyde) leads to effective disinfection without causing any detectable loss in sensor performance.

Alcohol-Based Sanitizers: An Effective Means for Preventing the Spread of Contagious Viral Diseases Including COVID-19

The global community is struggling with the highly contagious COVID-19. Returning to \normal life" now poses risks, and the use of appropriate protective measures has become necessary to continue daily life and protect public health. The main protective measures to prevent transmission of COVID-19 are masks, soaps and disinfectants. Because coronavirus is a \lipid-enveloped virus", it is very sensitive to lipid-dissolving chemicals and can therefore be effectively removed by washing hands sufficiently with soap and water. However, using an alcohol-based disinfectant is a more viable option for outdoor use. Alcohol-based disinfectants are inexpensive, immediately effective, easy to use and better tolerated by the skin compared to other disinfectants. WHO recommends disinfectants containing 75% isopropanol or 80% ethanol as highly effective in inactivating the SARS-CoV-2-virus. The current review discusses the role of alcohol-based hand sanitizers (ABHS) in preventing the spread of viruses, their side effects on human health, and suggests the use of alcohol-based sanitizers as potentially effective in combating the current epidemic.

Sans Standardization: Effective Endoscope Reprocessing

Bronchoscopy is a commonly performed procedure within thoracic and critical care medicine. Modern bronchoscopes are technologically advanced tools made of fragile electronic components. Their design is catered to allow maximum maneuverability within the semi-rigid tracheobronchial tree. Effective cleaning and reprocessing of these tools can be a challenge. Although highly functional, the design poses several challenges when it comes to reprocessing. It is a very important step, and lapses in the procedure have been tied to nosocomial infections. The process lacks universal standardization; several organizations have developed their own recommendations. Data have shown that key stakeholders are not fully versed in the essentials of endoscope reprocessing. A significant knowledge gap exists between those performing bronchoscopy and those who are stewards of effective endoscope reprocessing. To service as a resource for bronchoscopists, this study summarizes the steps of effective reprocessing, details the important elements within a health-care facility that houses this process, and reviews some of the current data regarding the use of disposable endoscopes.

Guidelines for Infection Control in the Urological Field, including Urinary Tract Management (revised second edition)

The Committee for the Development of Guidelines for Infection Control in the Urological Field, including Urinary Tract Management of the Japanese Urological Association, together with its systematic review team and external reviewers, have prepared a set of practice guidelines, an abridged version of which is published herein. These guidelines cover the following topics: (i) foundations of infection control, standard precautions, route-specific precautions, and occupational infection control (including vaccines); (ii) the relationship between urologists and infection control; (iii) infection control in urological wards and outpatient clinics; (iv) response to hepatitis B virus reactivation; (v) infection control in urological procedures and examinations; (vi) prevention of infections occurring in conjunction with medical procedures and examinations; (vii) responses to urinary tract tuberculosis and bacillus Calmette-Guérin; (viii) aseptic handling, cleaning, disinfection, and sterilization of urinary tract endoscopes (principles of endoscope manipulation, endoscope lumen cleaning, and disinfection); (ix) infection control in the operating room (principles of hand washing, preoperative rubbing methods, etc.); (x) prevention of needlestick and blood/bodily fluid exposure and response to accidental exposure; (xi) urinary catheter-associated urinary tract infection and purple urinary bag syndrome; and (xii) urinary catheter-associated urinary tract infections in conjunction with home care. In addressing these topics, the relevant medical literature was searched to the extent possible, and content was prepared for the purpose of providing useful information for clinical practice.

Recommendations for interventional pulmonology during COVID-19 outbreak: a consensus statement from the Portuguese Pulmonology Society

Coronavirus disease 2019 (COVID-19) is an emerging infectious disease caused by a novel SARS-CoV-2 pathogen. Its capacity for human-to-human transmission through respiratory droplets, coupled with a high-level of population mobility, has resulted in a rapid dissemination worldwide. Healthcare workers have been particularly exposed to the risk of infection and represent a significant proportion of COVID-19 cases in the worst affected regions of Europe. Like other open airway procedures or aerosol-generating procedures, bronchoscopy poses a significant risk of spreading contaminated droplets, and medical workers must adapt the procedures to ensure safety of both patients and staff. Several recommendation documents were published at the beginning of the pandemic, but as the situation evolves, our thoughts should not only focus on the present, but should also reflect on how we are going to deal with the presence of the virus in the community until there is a vaccine or specific treatment available. It is in this sense that this document aims to guide interventional pulmonology throughout this period, providing a set of recommendations on how to perform bronchoscopy or pleural procedures safely and efficiently.

Sanitizing agents for virus inactivation and disinfection

Viral epidemics develop from the emergence of new variants of infectious viruses. The lack of effective antiviral treatments for the new viral infections coupled with rapid community spread of the infection often result in major human and financial loss. Viral transmissions can occur via close human-to-human contact or via contacting a contaminated surface. Thus, careful disinfection or sanitization is essential to curtail viral spread. A myriad of disinfectants/sanitizing agents/biocidal agents are available that can inactivate viruses, but their effectiveness is dependent upon many factors such as concentration of agent, reaction time, temperature, and organic load. In this work, we review common commercially available disinfectants agents available on the market and evaluate their effectiveness under various application conditions. In addition, this work also seeks to debunk common myths about viral inactivation and highlight new exciting advances in the development of potential sanitizing agents.

A Prospective, Randomized Comparison of Duodenoscope Reprocessing Surveillance Methods

Duodenoscope use in healthcare facilities has been associated with transmission of multidrug resistant pathogens between patients. To assist healthcare facilities in monitoring the quality of their duodenoscope reprocessing procedures and limit patient risk of infection, the Centers for Disease Control and Prevention (CDC) deployed voluntary interim duodenoscope sampling and culturing surveillance protocols in 2015. Though the interim methods were widely adopted, alternative surveillance protocols were developed and implemented at individual institutions. Here, we compared two sampling methods-the 2015 CDC interim protocol and an alternative protocol developed by the University of Wisconsin Hospitals and Clinics (UWHC). We hypothesized that the UWHC protocol would detect a higher incidence of bacterial contamination from reprocessed duodenoscopes. A total of 248 sampling events were performed at UWHC. The CDC protocol (n = 129 sampling events) required culturing samples collected from each duodenoscope after brushing its terminal end and flushing its lumen with sterile water. The UWHC protocol (n = 119 sampling events) required culturing samples collected from each duodenoscope after swabbing its elevator, immersing its terminal end into broth and flushing its lumen with saline. With the CDC method, 8.53% (n = 11) of the duodenoscopes sampled were positive for bacterial growth with 15 isolates recovered. Using the UWHC method, 15.13% (n = 18) of cultures were positive for bacterial growth with 20 isolates recovered. The relative risk of identifying a contaminated duodenoscope using the CDC interim method, however, was not different than when using the UWHC protocol. Mean processing time (27.35 and 5.11 minutes, p < 0.001) and total cost per sample event ($17.87 and $15.04) were lower using the UWHC method. As the UWHC protocol provides similar detection rates as the CDC protocol, the UWHC method is useful, provided the shorter processing time and lower cost to perform.

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.

Hydrogen peroxide and sodium hypochlorite disinfectants are more effective against Staphylococcus aureus and Pseudomonas aeruginosa biofilms than quaternary ammonium compounds

Background

Antimicrobial disinfectants are used as primary treatment options against pathogens on surfaces in healthcare facilities to help prevent healthcare associated infections (HAIs). On many surfaces, pathogenic microorganisms exist as biofilms and form an extracellular matrix that protects them from the antimicrobial effects of disinfectants. Disinfectants are used as all-purpose antimicrobials though very few specifically make biofilm efficacy claims. The objective of this study was to evaluate the efficacy of eight registered disinfectants (six registered by the Environmental Protection Agency and two products registered in by the European Chemical Agency) with general bactericidal claims, but currently no biofilm efficacy claims, against Staphylococcus aureus ATTC-6538 and Pseudomonas aeruginosa ATCC-15442 biofilms. We hypothesized that hydrogen peroxide and sodium hypochlorite disinfectant products would be more effective than quaternary ammonium chlorides.

Methods

This study tested the bactericidal efficacy of eight registered disinfectant products against S. aureus ATCC-6538 and P. aeruginosa ATCC-15442 grown on glass coupons using a Center for Disease Control (CDC) biofilm reactor and EPA MLB SOP MB-19. Bactericidal efficacy was determined after treating coupons with disinfectants following standard EPA MLB SOP MB-20.

Results

Overall, sodium hypochlorite and hydrogen peroxide disinfectants had significantly higher bactericidal efficacies than quaternary ammonium chloride disinfectants. We also found that all tested disinfectants except for quaternary ammonium chloride disinfectants met and exceeded the EPA standard for bactericidal efficacy against biofilms.

Conclusion

In general, bactericidal efficacy against biofilms differed by active ingredient. The efficacies of sodium hypochlorite and hydrogen peroxide disinfectants did not vary between strains, but there were significant differences between strains treated with quaternary ammonium chloride disinfectants.

Morphological bactericidal fast-acting effects of peracetic acid, a high-level disinfectant, against Staphylococcus aureus and Pseudomonas aeruginosa biofilms in tubing

Background

The bactericidal effect of disinfectants against biofilms is essential to reduce potential endoscopy-related infections caused by contamination. Here, we investigated the bactericidal effect of a high-level disinfectant, peracetic acid (PAA), against Staphylococcus aureus and Pseudomonas aeruginosa biofilm models in vitro.

Methods

S. aureus and P. aeruginosa biofilms were cultured at 35 °C for 7 days with catheter tubes. The following high-level disinfectants (HLDs) were tested: 0.3% PAA, 0.55% ortho-phthalaldehyde (OPA), and 2.0% alkaline-buffered glutaraldehyde (GA). Biofilms were exposed to these agents for 1–60 min and observed after 5 min and 30 min by transmission and scanning electron microscopy. A Student’s t test was performed to compare the exposure time required for bactericidal effectiveness of the disinfectants.

Results

PAA and GA were active within 1 min and 5 min, respectively, against S. aureus and P. aeruginosa biofilms. OPA took longer than 10 min and 30 min to act against S. aureus and P. aeruginosa biofilms, respectively (p < 0.01). Treatment with PAA elicited changes in cell shape after 5 min and structural damage after 30 min.

Conclusions

Amongst the HLDs investigated, PAA elicited the most rapid bactericidal effects against both biofilms. Additionally, treatment with PAA induced morphological alterations in the in vitro biofilm models, suggesting that PAA exerts fast-acting bactericidal effects against biofilms associated with endoscopy-related infections. These findings indicate that the exposure time for bactericidal effectiveness of HLDs for endoscope reprocessing in healthcare settings should be reconsidered.

Acute Glutaraldehyde Mucosal Injury of the Upper Aerodigestive Tract Due to Damage to the Working Channel of an Endoscope

Objectives

Glutaraldehyde (Cidex) is a commonly used agent for cold sterilization of endoscopes despite its known irritative, allergic, and carcinogenic potential. This report details the clinical course of 2 patients who suffered acute glutaraldehyde exposure during office injection procedures.

Methods

Clinical records of 2 outpatients undergoing office injection procedures were reviewed. One patient underwent bilateral injections of hydroxyapatite, and 1 underwent voice gel injection.

Results

Both patients developed acute mucosal injury in the form of supraglottitis and laryngitis. Both patients required inpatient admission with airway monitoring (1 requiring admission to the intensive care unit) and were treated with steroids and antibiotics. The same channel endoscope was used for both procedures and was noted after careful examination to have retained glutaraldehyde inside the scope due to a perforation of the lining of the working channel.

Conclusions

Glutaraldehyde can cause acute mucosal injury to supraglottic and glottic structures, and diligent procedures must be maintained for flushing the channels and monitoring glutaraldehyde retention in the channels. Great care should be taken to avoid damage to the lining of working channels from instrumentation.

Evaluation of three different decontamination techniques on biofilm formation, and on physical and chemical properties of resin composites

OBJECTIVES

This study evaluated three different sterilization/disinfection techniques for resin composites on bacterial growth and surface modification after decontamination.

METHODS

Two resin composites were sterilized/disinfected with three different techniques: UV light, 1% chloramine T, and 70% ethanol. Four different times were used for each technique to determine the shortest time that the solution or UV light was effective. The influence of sterilization/disinfection technique on bacterial growth was evaluated by analyzing the metabolic activity, using the AlamarBlue™ assay, bacterial viability, and SEM images from biofilms of Streptococcus mutans. The surface change, after the process, was analyzed with ATR/FTIR and SEM images. The solutions used for decontamination (1% chloramine-T and 70% ethanol) were analyzed with ¹ H-NMR to identify any resin compounds leached during the process.

RESULTS

One minute of decontamination was efficient for all three methods tested. Chloramine-T increased the surface porosity on resin composites, no changes were observed for UV light and 70% ethanol, however, ¹ H-NMR identified leached monomers only when 70% ethanol was used. No chemical change of the materials was found under ATR/FTIR analyses after the decontamination process. Chloramine-T, with no previous wash, increased the bacterial viability for both resin composites and increased the bacterial metabolism for the resin composite without fluoride.

CONCLUSION

UV light had no interference on the resin composites properties tested using 1 min of exposure compared to the other decontamination methods. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 945-953, 2018.

Evaluation of the Antimicrobial Activity and Materials Compatibility of Orthophthalaldehyde as a High-level Disinfectant

We tested the antimicrobial activity of orthophthalaldehyde (OPA) against 21 strains (16 species) of pathogenic microorganisms that cause hospital-associated infections. Changes in hepatitis B surface antigen (HBs-Ag) resulting from the addition of OPA to HBs-Ag-positive serum were measured using a radio-immunoassay. We also examined the effect of immersing medical instruments in OPA (0.55%) for 168 h at room temperature. OPA (0.5%, 0.37% and 0.25%) killed 11 strains of vegetative bacteria within 15 s, and it killed the test microorganisms faster than 3.0% glutaraldehyde (GTA). Incubation with OPA or GTA caused levels of HBs-Ag to fall below a cut-off value within 30 s. OPA did not adversely affect instruments made from various materials. OPA demonstrated more effective antimicrobial activity than GTA against a range of microorganisms. We conclude that OPA should replace GTA as the first-choice high-level disinfectant for endoscopes, considering its antimicrobial efficacy and low inhalation toxicity.

Evaluation of a novel commercial quaternary ammonium compound for eradication of Mycobacteria, HCV and HBV in Egypt

Endoscopes are a common source of outbreaks of healthcare-associated infections. It is therefore important to identify high-level disinfectants capable of eliminating or killing all vegetative bacteria, mycobacteria, and viruses. Aldehydebased disinfectants are most commonly used in clinical practice but resistance has recently been detected and side effects associated with these disinfectants are well documented. In this study, we evaluated Virusolve+® EDS, a novel quaternary ammonium compound formulation supplied by Amity international, against Mycobacterium bovis (ATCC-27289), hepatitis C virus (HCV)-positive serum and hepatitis B surface antigen-positive serum. We also compared its efficacy against Cidex® (glutaraldehyde 2%), an aldehyde-based disinfectant. M. bovis showed no growth after 10 weeks with either Virusolve+® or Cidex®. Virusolve+® achieved a 10(4)- fold reduction in the initial 10(6) HCV load under clean conditions (without red blood cells) for 20 min, whereas Cidex® achieved this reduction under clean and dirty conditions (without and with red blood cells, respectively) after both 10 and 20 min. Both Virusolve+® and Cidex® were able to eradicate hepatitis B virus (HBV) infectivity under clean conditions after 10 and 20 min, whereas under dirty conditions they were only able to eradicate virus infectivity after 20 min. Virusolve+® EDS when compared with Cidex® showed equal mycobactericidal activity completely eradicating M. bovis. However, both showed comparable virucidal activity against HBV, which was more effective under clean conditions, emphasizing the importance of the cleaning step in endoscope reprocessing. Cidex® was more effective at eradicating HCV under dirty conditions after a short contact time.

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.

Synergistic sporicidal effect of ethanol on a combination of orthophthalaldehyde and didecyldimethylammonium chloride

The objective of this study was to evaluate the potential synergistic effect of ethanol on a combination of orthophthalaldehyde (OPA) and didecyldimethylammonium chloride (DDAC) against the spores of Bacillus subtilis var. Niger. The quantitative carrier test for sporicidal testing of high-level disinfectants according to the guideline of China (Technical Standard for Disinfection 2002) was used as method. Considerable synergistic effect was observed after a 30-min treatment at 20°C. There was an augment in mean log reduction as the concentration of DDAC was increased ranging from 0·2 to 3 g l(-1) in combination with 6 g l(-1) OPA. Ten and 20% ethanol in combination with 6 g l(-1) OPA and 2 g l(-1) DDAC caused more than a 3-log reduction while either 6 g l(-1) OPA, 2 g l(-1) DDAC and 20% ethanol alone or a combination of two of the three agents produced less than a 1-log reduction. Further, 40-min exposure time of combination of OPA, DDAC and 20% ethanol led to greater than a 5-log reduction in spores, and no spore growth was observed following 60- and 90-min exposures.

SIGNIFICANCE AND IMPACT OF THE STUDY

Orthophthalaldehyde (OPA) is very effective at concentrations far lower than its recommended in-use concentration of 0·5% (w/v) and is equally effective against both the gram-negative and gram-positive bacteria. However, it shows lower activity against spores. The synergistic sporicidal effect exhibited by ethanol on a combination of OPA and DDAC can be considered to enhance sporicidal activity for using in situations of sterilization, to reduce in-use concentration of OPA used alone, which may minimize its side effect. OPA may be a more satisfactory and the first-choice agent to replace glutaraldehyde (GTA) as a high-level disinfectant for medical devices.

Effective analysis of the use of peracetic acid after instrumentation of root canals contaminated with Enterococcus faecalis

INTRODUCTION

The aim of this study was to evaluate the effectiveness of peracetic acid (PAA) in cleaning root canals contaminated with Enterococcus faecalis.

METHODS

Sixty first and second mandibular molars were used. Their mesiobuccal canals were prepared with the Reciproc System (VDW, Munich, Germany). The canals were irrigated with 10 mL saline during instrumentation. The teeth were randomly divided into 3 groups (n = 20), according to the irrigation solution to be used after instrumentation: group PAA (5 mL 1% PAA), group EDTA/sodium hypochlorite (NaOCl) (5 mL 17% EDTA followed by 5 mL 2.5% sodium hypochlorite), and group S (5 mL saline). Microbiological samples were collected before instrumentation and after final irrigation. Bacterial quantification was performed by counting the number of colony-forming units (CFUs/mL). The results were analyzed by the nonparametric Wilcoxon and Kruskal-Wallis tests.

RESULTS

The 3 groups showed a significant reduction (P < .05) in CFUs/mL after final irrigation. PAA and NaOCl associated with EDTA produced a significantly higher reduction in CFUs/mL (P < .05) compared with saline. There was no statistically significant difference between PAA and EDTA + 2.5% NaOCl (P > .05).

CONCLUSIONS

According to the results of the present study, the effectiveness of 1% PAA was similar to that of 17% EDTA + 2.5% NaOCl in cleaning curved root canals contaminated with E. faecalis.

Isolation, pathogenicity and disinfection of Staphylococcus aureus carried by insects in two public hospitals of Vitória da Conquista, Bahia, Brazil

Currently, hospital infection is a serious public health problem, and several factors may influence the occurrence of these infections, including the presence of insects, which are carriers of multidrug-resistant bacterial species. The aim of this study was to isolate staphylococci carried by insects in two public hospitals of Vitoria da Conquista, Bahia and to identify the resistance profile, pathogenicity and efficacy of disinfection of the premises. A total of 91 insects were collected in 21 strategic points of these hospitals, and 32 isolated strains of Staphylococcus aureus were isolated. Based on antibiogram and Minimum Inhibitory Concentration results, 95% of these strains were susceptible to oxacillin. These strains were also evaluated for the presence of resistance genes encoding resistance to oxacillin/methicillin by polymerase chain reaction, but the sample was negative for this gene. Pathogenicity tests were performed in vitro biofilm formation induced by glucose, where it was found that eight (27.58%) strains were classified as biofilm producers and 21 (72.4%) as stronger producers. In addition, we performed PCR for their virulence genes: Sea (enterotoxin A), SEB (B), Sec (C), PVL (Panton-Valentine Leukocidin), ClfA (clumping factor A) and Spa (protein A). Of these, Sea, Spa PVL were positive in 7 (21.8%), 2 (6.3%) and 1 (3.1%) samples, respectively. The analysis of cytokine induction in the inflammatory response of J774 macrophages by isolates from the two hospitals did not show statistical difference at the levels of IL-6, TNF-α, IL-1 and IL-10 production. In addition, we verified the antimicrobial activity of disinfecting agents on these strains, quaternary ammonium, 0.5% sodium hypochlorite, 1% sodium hypochlorite, 2% sodium hypochlorite, 2% glutaraldehyde, Lysoform^®, 70% alcohol solution of chlorhexidine digluconate, 2% peracetic acid, and 100% vinegar. Resistance was seen in only for the following two disinfectants: 70% alcohol in 31 (96.8%) samples tested and vinegar in 30 (93.8%) samples. The study demonstrated the presence of resistant and pathogenic organisms conveyed by insects, thus suggesting improvement in efforts to control these vectors.

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.

Efficacy of peracetic acid in rapid disinfection of Resilon and gutta-percha cones compared with sodium hypochlorite, chlorhexidine, and povidone-iodine

BACKGROUND

The aim of this investigation was to compare the effectiveness of 3% sodium hypochlorite (NaOCl), 2% chlorhexidine, 1% peracetic acid, and 10% povidone-iodine in the rapid disinfection of Resilon (Pentron Clinical Technologies, LLC, Wallingford, CT) and gutta-percha cones contaminated with Enterococcus faecalis and Bacillus subtilis.

METHODS

Two hundred fifty-six samples consisting of 128 gutta-percha cones and 128 Resilon cones were used in this study. The materials were tested for disinfection according to the type of solution (3% NaOCl, 2% chlorhexidine, 1% peracetic acid, or 10% povidone-iodine), the time of exposure to each solution (1 or 5 minutes), and the type of microorganisms (E. faecalis or B. subtilis). Subsequent to the disinfection, samples were placed in test tubes containing 10 mL Mueller-Hinton broth and incubated at 37°C for 7 days. All test tubes were observed at 24-hour intervals and visually checked for turbidity, signifying microbial growth.

RESULTS

In this study, 1% peracetic acid showed the best results for both 1 minute and 5 minutes of disinfection, 2% chlorhexidine showed the second best results although it was statistically at par with peracetic acid, and 3% hypochlorite ranked third in disinfection; this was statistically significant when compared with peracetic acid and chlorhexidine. Disinfection by povidone-iodine was the least within all the groups for both contact times although disinfection for 5 minutes showed better results than disinfection for 1 minute for gutta-percha.

CONCLUSIONS

The outcome of this study confirmed the efficacy of 1% peracetic acid and 2% chlorhexidine in the rapid disinfection of both Resilon and gutta-percha.

Adverse staff health outcomes associated with endoscope reprocessing

There are occupational challenges associated with cleaning, disinfecting, storing, and transporting flexible endoscopes. Although the Occupational Safety and Health Administration (OSHA) has set standards to protect the safety of health workers in the United States, the standards are not specific to endoscope reprocessing, and the general standards that are in place are not fully implemented. Furthermore, adverse staff outcomes may not be fully preventable. To assess the evidence for adverse outcomes in staff associated with endoscope reprocessing, a literature review was performed in the PubMed database for articles on this topic published between Jan. 1, 2007 and March 7, 2012. Eight studies were identified, mainly European, which reported numerous adverse outcomes to healthcare personnel associated with endoscope reprocessing including respiratory ailments and physical discomfort. More scientifically rigorous studies are required to comprehensively describe adverse health outcomes in personnel engaged in reprocessing, particularly in the United States, and examine whether increased automation of the reprocessing process leads to decreased adverse health outcomes for staff.

Disinfection and sterilization: an overview

All invasive procedures involve contact by a medical device or surgical instrument with a patient's sterile tissue or mucous membranes. The level of disinfection or sterilization is dependent on the intended use of the object: critical (items that contact sterile tissue such as surgical instruments), semicritical (items that contact mucous membrane such as endoscopes), and noncritical (devices that contact only intact skin such as stethoscopes) items require sterilization, high-level disinfection, and low-level disinfection, respectively. Cleaning must always precede high-level disinfection and sterilization.

Allergy to ortho-phthalaldehyde in the healthcare setting: advice for clinicians

This study summarizes and reviews the available health information on ortho-phthalaldehyde (OPA), a recently introduced and widespread disinfectant for heat-sensitive medical equipment, particularly focusing on its possible immunological effects in the healthcare setting. OPA properties derived from laboratory and clinical studies, and in vivo and in vitro tests for the diagnosis of OPA allergy are described. The available evidence suggests the spreading of OPA as disinfectant in endoscopy units despite the little available scientific evidence on its safety. Indeed, some papers reported on serious adverse reactions to OPA in patients and, to a lesser extent, in exposed workers, and in vivo studies suggested that OPA is a dermal and respiratory sensitizer. Finally, until more definite safety data become available only suggestions on possible preventive measures can be provided.

Glutaraldehyde exposure and its occupational impact in the health care environment

Despite the search for effective and less toxic substitutes, glutaraldehyde (GA) remains one of the few substances capable of high-level instrument disinfection in modern health care. Workers commonly affected include operating room nurses, radiographers, x-ray technicians and cleaners. Widespread hospital usage combined with its well-known irritant properties, has ensured an increase in occupationally-related illnesses during recent years. Operating room nurses, laboratory workers and x-ray technicians frequently contact GA in both the liquid and vapor form. Workplace exposure is usually dependent on job tasks, ventilation levels and the use of protective equipment. GA is a relatively potent irritant and sensitizer, with a well-documented history of symptoms following occupational exposure. Although mechanisms for GA toxicity have been postulated, research on the toxicological, teratogenic, and carcinogenic potential of this chemical has shown inconsistent results. Reducing workplace exposure to its lowest possible level represents the most important hazard reduction strategy. This may be achieved by keeping GA containers tightly sealed when not in use, maintaining adequate ventilation levels and the rigid adherence to appropriate personal protective equipment. Substitution with automated cold sterilization machines may be another appropriate measure, while banning unnecessary practices such as GA fogging and its use as a surface disinfectant may also be helpful in reducing occupational exposure in the health care environment.

Guidelines for transoesophageal echocardiographic probe cleaning and disinfection from the British Society of Echocardiography

The clinical utility of transoesophageal echocardiography (TOE) is well established. Being a semi-invasive procedure, however, the potential for transmission of infection between sequential patients exists. This has implications for the protection of both patients and medical staff. Guidelines for disinfection during gastrointestinal endoscopy (GIE) have been in place for many years.(1,2) Unfortunately, similar guidance is lacking with respect to TOE. Although traversing the same body cavities and sharing many similarities with upper GIE, there are fundamental structural and procedural differences with TOE which merit special consideration in establishing a decontamination protocol. This document provides recommendations for TOE probe decontamination based on the available evidence, expert opinion, and modification of the current British Society of Gastroenterology guidelines.

Current status of cleaning and disinfection for gastrointestinal endoscopy in China: a survey of 122 endoscopy units

BACKGROUND

Adequate compliance with the existing guidelines for cleaning and disinfection of gastrointestinal endoscopes and accessories is necessary to obtain high-level disinfection and prevent pathogen transmission.

AIM

To investigate cleaning and disinfection practice in China.

METHODS

A questionnaire with 21 questions concerning gastrointestinal endoscopy reprocessing was sent by e-mail to 189 endoscopy units in China.

RESULTS

One hundred and twenty-two (80.39%) of the 189 units responded. Compared with the low-workload units (<5000 procedures/year), the high-workload units (≥5000 procedures/year) had a significantly higher number of gastrointestinal endoscopes (25.8 ± 3.6 vs. 4.7 ± 1.8, p < 0.01) and the higher possessing rate of automated endoscope reprocessors (43.9% vs. 3.1%, p<0.01). Glutaraldehyde was the most commonly employed disinfectant (88.5%) in all the units. In 23/122 (18.8%) units, the exposure time to glutaraldehyde was <45 min in the case of infectious disease patients. Eighty-six of 122 (70.5%) units reused disposable materials, of which 21/86 (24.4%) reused disposable forceps and disposable polypectomy hooks, and 2/86 (1.6%) reused disposable injection needles intermittently.

CONCLUSION

Although gastrointestinal endoscopy has developed rapidly in China in the past decade, there is still room for improvement in the practice of endoscopy reprocessing, especially in middle-sized and small cities.

Reducing infection risk in colonoscopy

Colonoscopy is a well recognized diagnostic and therapeutic tool. Endoscope reprocessing must be done correctly every time; a breach of protocol leading to transmission of infection has the potential to bring endoscopy to a halt. Standards exist that guide the practitioner in all health care settings to minimize the chance of transmission of infection. Safe injection practices and reprocessing of endoscopes using high-level disinfection and sterilization methods may help avert the risk of contracting possible infections during colonoscopy procedures.

Oropharyngeal and Laryngeal Burn Resulting from Exposure to Endoscope Disinfectant: A Case Report

Iatrogenic injury from medical disinfectants is an uncommon but potentially devastating complication. We report an unusual, but severe, upper aerodigestive complication from the use of ortho- Phthalaldehyde solution, a commonly used endoscope disinfectant.

Survival of enveloped and non-enveloped viruses on surfaces compared with other micro-organisms and impact of suboptimal disinfectant exposure

Survival of enveloped and non-enveloped viruses was compared with that of bacteria, yeasts and mycobacteria when dried on the surface of polyvinyl chloride test carriers in the presence or absence of an organic matrix. The efficacy of glutaraldehyde and accelerated hydrogen peroxide (AHP) disinfectants was evaluated. Reovirus, a non-enveloped virus, persisted and had a RF of 2 after 30 days whereas Enterococcus faecalis had an RF of 4 over the same time period. The other test organisms (Sindbis virus, Pseudomonas aeruginosa, Mycobacterium chelonae and Candida albicans) had variable survivals but none survived as long as 30 days. Both glutaraldehyde and AHP were effective at manufactures' recommended dilutions for high-level disinfection. However, only 7% AHP eliminated a glutaraldehyde-resistant strain of M. chelonae. Breakthrough survival was detected at 0.1% glutaraldehyde and 0.05% AHP for all organisms tested. Our data emphasise the need for effective cleaning and disinfection in nosocomial settings to prevent pathogen transmission.