Washer Disinfector Research Articles

A multicenter study comparing the bacterial reduction on flexible endoscopes without a working channel between UV-C light disinfection versus standard endoscope Washer Disinfection: a randomized controlled trial

BackgroundTo prevent cross-contamination between patients, adequate reprocessing is necessary when using flexible endoscopes (FEs) without a working channel. The current reprocessing process using an Endoscope Washer Disinfector (EWD) is time-consuming. Ultraviolet light group C (UV-C) exposition is an alternative and fast disinfection method and has previously been shown to adequately reduce Colony Forming Units (CFUs) on FEs without a working channel. The objective of this study was to examine whether UV-C light is as effective in reducing CFUs on contaminated FEs without a working channel compared to the EWD.MethodsFEs without a working channel were collected in three different Otorhinolaryngology Departments in the Netherlands. After pharyngolaryngoscopy, a manual pre-cleaning with tap water was performed and a culture was collected by rolling the distal 8–10 cm of the FE over an agar plate. Next, the FE was randomly assigned to be disinfected with UV-C light (D60) or the EWD (gold standard). After disinfection, another culture was taken. The primary outcome was microbiological contamination, defined by Colony Forming Units (CFU).Results600 FEs without a working channel were randomized. After clinical use and manual pre-cleaning, 239/300 (79.7%) FEs in the UV-C group and 262/300 (87.3%) FEs in the EWD group were contaminated (i.e., > 0 CFU). FEs without culture confirmed contamination were excluded from further analysis. After UV-C light disinfection, 195/239 (81.6%) FEs showed 0 CFUs, compared to 187/262 (71.4%) FEs disinfected with the EWD (p < 0.01). A multivariate logistics regression analysis showed an increased odds of 0 CFUs when using UV-C light (OR 1.83, 95% CI 1.19–2.79; p < 0.01), conditional on participating hospitals and types of FE.ConclusionsUV-C light disinfection of FEs without a working channel appears more effective in reducing CFUs compared to the EWD and might be a good alternative disinfection method.Trial registrationNot applicable.

Is ultraviolet light disinfection fit to be the future standard for the disinfection of flexible endoscopes without a working channel?

To investigate colony-forming unit (CFU) reduction on contaminated flexible endoscopes (FEs) without a working channel after UV-C light disinfection, compared to the current disinfection method with the endoscope washer disinfector (EWD). After pharyngolaryngoscopy, a manual pre-cleaning with tap water was performed. A culture was then collected by rolling the distal 8-10 cm of the FE over an Agar plate. The FE was disinfected using the D60 (60-s disinfection process with UV-C light) or the EWD (gold standard reprocessing process with water and chemicals). Another culture was then taken. After incubation, a CFU count was performed. A total of 200 FEs without a working channel were divided equally between the two disinfection groups. After clinical use and manual pre-cleaning, 84 of the 100 (84.0%) (UV-C light group) and 79 of the 100 (79.0%) (EWD) FEs were contaminated with at least 1 CFU. FEs that showed no contamination after use were excluded from further analysis. After disinfection with UV-C light, 72 (85.7%) FEs showed no contamination (i.e., 0 CFUs) versus 66 (83.5%) FEs after reprocessing with the EWD. There is no difference in CFUs reduction on contaminated FEs without a working channel between UV-C light disinfection and the current gold standard, the EWD.

Achieving best practice with a washer disinfector

Achieving best practice with a washer disinfector

Achieving best practice with a washer disinfector.

Achieving best practice with a washer disinfector.

Environmental Contamination and Persistence of Clostridioides difficile in Hospital Wastewater Systems.

Clostridioides difficile produces an environmentally resistant dormant spore morphotype that infected patients shed to the hospital environment. C. difficile spores persist in clinical reservoirs that are not targeted by hospital routine cleaning protocols. Transmissions and infections from these reservoirs present a hazard to patient safety. This study aimed to assess the impact of patients acutely suffering from C. difficile-associated diarrhea (CDAD) on C. difficile environmental contamination to identify potential reservoirs. Twenty-three hospital rooms accommodating CDAD inpatients with corresponding soiled workrooms of 14 different wards were studied in a German maximum-care hospital. Additionally, four rooms that never accommodated CDAD patients were examined as negative controls. Stagnant water and biofilms from sinks, toilets, and washer disinfector (WD) traps as well as swabs from cleaned bedpans and high-touch surfaces (HTSs) were sampled. For detection, a culture method was used with selective medium. A latex agglutination assay and a Tox A/B enzyme-linked immunosorbent assay were performed with suspect colonies. Stagnant water and biofilms in hospital traps (29%), WDs (34%), and HTSs (37%) were found to be reservoirs for large amounts of C. difficile during the stay of CDAD inpatients that decreased but could persist 13 ± 6 days after their discharge (13%, 14%, and 9.5%, respectively). Control rooms showed none or only slight contamination restricted to WDs. A short-term cleaning strategy was implemented that reduced C. difficile in stagnant water almost entirely. IMPORTANCE Wastewater pipes are microbial ecosystems. The potential risk of infection emanating from the wastewater for individuals is often neglected, since it is perceived to remain in the pipes. However, sewage systems start with siphons and are thus naturally connected to the outside world. Wastewater pathogens do not only flow unidirectionally to wastewater treatment plants but also retrogradely, e.g., through splashing water from siphons to the hospital environment. This study focused on the pathogen C. difficile, which can cause severe and sometimes fatal diarrheas. This study shows how patients suffering from such diarrheas contaminate the hospital environment with C. difficile and that contamination persists in siphon habitats after patient discharge. This might pose a health risk for hospitalized patients afterward. Since this pathogen's spore morphotype is very environmentally resistant and difficult to disinfect, we show a cleaning measure that can almost entirely eliminate C. difficile from siphons.

SG-APSIC1045: A quantitative assessment of ATP bioluminescence on dental instruments reprocessed by automated washer-disinfector and ultrasonic machine

Objectives: Dental instruments are contaminated by blood and saliva during dental procedures. To prevent cross infection, all contaminants should be removed from the surfaces of instruments. Inadequate cleaning can hinder disinfection and sterilization process. To compare the cleaning efficacy of an automated washer–disinfector versus an ultrasonic machine on dental instruments, adenosine triphosphate (ATP) measurements were compared. Methods: From National University Polyclinic Bukit Panjang Dental Services, we collected 2 loads of 40 dental instruments previously used in dental treatments: extraction forceps, high-volume suction tips, Coupland elevators, matrix band holders, and ultrasonic scaler tips. At the point of use, gross soil was wiped from instrument surfaces with water. Each instrument was swabbed after cleaning either using a washer–disinfector or an ultrasonic machine. The relative light units (RLU) on the luminometer indicated the amount of ATP contaminants and residue bioburden present on the instruments. Results: The mean RLU values across all instruments in the washer–disinfector group was 2.5 times lower than the mean value of the instruments in the ultrasonic group (35.4 vs 89.9 RLU). This difference was statistically significant for all instrument groups except for the high-volume suction tips. The Mann-Whitney U test indicated that the RLU in the ultrasonic group was higher than the RLU for the washer–disinfector group for extraction forceps (P &lt; .001), ultrasonic scaler tips (P &lt; .023), and matrix bands (P &lt; .006). A t test indicated the same relationship for Coupland elevators (P &lt; .005). Conclusions: The mean RLU values for both cleaning methods were lower than the manufacturer’s benchmark (RLU ≤ 150), suggesting that both methods can achieve effective cleaning. However, cleaning using an automated washer–disinfector is significantly more effective than an ultrasonic machine for nonlumen instruments. The effectiveness of cleaning using ultrasonic machine varied greatly among different types of instruments with different design complexities.

Study of Organisation and Work Management of Central Sterile Supply Department of a Tertiary Care Hospital in Punjab

Background: Healthcare associated infections continue to remain a major challenge in all healthcare settings. Central sterile supply department (CSSD) plays a key role in combating these infections by providing optimum level of sterilization and disinfection. The objective of our study was to study the workflow management of CSSD of a tertiary care institution. Methods: This observational study was carried out from October 2021 to December 2021. Prior permission was obtained from appropriate authority before conducting the study. Results: CSSD of the institution is located in the basement area within the hospital premises with adequate staff. Linen, OT instruments, dressings and trays are sterilized in the CSSD. The CSSD is well equipped with autoclaves, ETO machines and washer disinfector. Being a NABH certified hospital, physical, chemical and biological indicators are used during sterilization process. Conclusion: Quality of standards of CSSD procedures are well maintained and CSSD has immense contribution in maintaining the standards of sterilization in the hospital.

Improved surveillance of surgical instruments reprocessing following the variant Creutzfeldt–Jakob disease crisis in England: findings from a three-year survey

Sensitive, direct protein-detection methods are now recommended for the inspection of reprocessed reusable surgical instruments in England to reduce the risk of prion transmission. To implement an established, highly sensitive method to quantify proteinaceous residues on reprocessed instruments in a Sterile Services Department (SSD) and evaluate its potential impact on service provision. We introduced highly sensitive epifluorescence (EDIC/EF) microscopy in a large SSD. Over three years, we periodically tested two models of washer disinfector using stainless-steel tokens spiked with mouse brain homogenate or Browne test soil for comparison. We also obtained data and feedback from staff who had been using EDIC/EF to examine almost 3000 reprocessed instruments. All reprocessed test surfaces harboured residual contamination (up to 258.4 ng from 1-μg spikes). Proximity between surfaces affected decontamination efficacy and allowed cross-contamination. Up to 50 ng de novo proteinaceous contamination was deposited on control surfaces after a single automated washer disinfector (AWD) cycle. The test soil behaved differently than real tissue contamination. SSD staff observed proteinaceous residues on most reprocessed instruments using EDIC/EF, which can detect far smaller amounts than the currently accepted national threshold of 5 μg per side. Implementing recent national guidelines to address the prions concern proved an eye-opener. Microscopic levels of proteins remain on many reprocessed instruments. The impact most of these residues, potentially including prions, may have on subsequent patients after sterilization remains debatable. Improving surveillance capability in SSDs can support decision making and raise the standards of surgical instruments reprocessing.

Rinse performance evaluation by measuring the residual amount of detergent contained in the rinse effluent of washer-disinfector

The residual amounts of detergent that remains on medical instruments after insufficient rinsing not only causes discoloration and corrosion, but it can also have some adverse effects on the human body. In this study, we measured amounts of chemical elements included in the detergent with inductivity coupled plasma (ICP) optical emission spectrometry in addition to the commonly used washer-disinfector (WD) rinsing evaluation method. We also attempted to identify the factors that could influence rinsing. Furthermore, cytotoxicity tests were performed to determine the concentration on how much the detergent was toxic to cells.

Washer disinfector and alkaline detergent efficacy against C. difficile on plastic bedpans

Clostridioides difficile is a major cause of infectious antibiotic resistant diarrhea. C. difficile spores are shed in patient stool, are hearty and difficult to kill. Bedpans are often used by patients with C. difficile infections and require proper handling and cleaning or disposal to prevent the transmission of C. difficile spores and other infectious microorganisms into the environment. Disposable bedpans are often used for convenience, which has consequences from an environmental sustainability perspective. This study evaluates the ability for a washer-disinfector device (WD) to efficaciously clean and disinfect C. difficile spores and Escherichia coli from bedpans for sanitary reuse. A commercially available WD device was evaluated for both efficacy and thermal disinfection against C. difficile spores and Escherichia coli using one disinfection cycle per test. Bedpans were not rinsed or dumped prior to placement in the WD. Bedpans were sampled using swabs. Microorganisms were eluted from the swabs and log-kill was calculated. The average log-kill for C. difficile spores was 3.99 and >7.69 for E. coli. Thermal disinfection results showed an average log kill of 4.31 for C. difficile and >7.23 for E. coli. The WD was efficacious against both C. difficile spores and E. coli when used according to manufacturer's instructions for use, suggesting a viable alternative to disposable bedpan waste management.

Corrosion Generation and Cleaning Effect on Surgical Instruments with Attached Radiofrequency Identification Tags in Long-Term Usage.

Background: Faulty cleaning of surgical instruments may lead to corrosion damage and a higher risk of surgical site infection. We have developed a method in which each instrument has an attached radiofrequency identification (RFID) tag for individual management. However, because of the structure of the instruments, a risk of corrosion from poor cleaning exists; therefore, observation during long-term usage is necessary.Methods: The cleaning effect at the jig of the RFID tag was verified by the amount of residual protein left by various cleaning methods. In our investigation of long-term usage, we examined 94 surgical instruments with RFID tags used in the operating room for 50 months employing a microscope to identify any corrosion at the jig.Results: The method using a washer disinfector (WD) was found to be highly effective. From observation after long-term usage, friction by the RFID tag occurred in about 70% of the jigs. However, no pitting or general corrosion was seen.Conclusions: When WD is used properly, there is only a minor risk of residual protein, and corrosion does not occur even with long-term use. By using surgical instruments with RFID tags, it is possible to determine the number of uses and the history at the individual level. This facilitates operation of safe surgical instruments by limiting the number of times a particular instrument is used.

Assessing the efficacy and cost of detergents used in a primary care automated washer disinfector.

Cleaning of re-usable medical devices is a critical control point in the decontamination cycle, although defined end-points of the process are controversial. Investigate cleaning efficacy and cost of different detergent classes in an automated washer disinfector (AWD) designed for dental practice. Loads comprised test soiled dental hand instruments in cassettes and extraction forceps. Residual protein assayed using the International standard method (ISO 15883-5:2005) 1% SDS elution with ortho-phthalaldehyde (OPA) or GBox technology (on instrument OPA analysis). Short (60 minutes) and long (97 minutes) AWD cycles were used with four different classes of detergents, tap water and reverse osmosis water. SDS elution analysis (N = 612 instruments) demonstrated four detergents with both wash cycles achieved equivalent cleanliness levels and below a threshold of 200 μg protein/instrument. GBox methodology (N = 575) using UK Department of Health threshold of 5 μg/instrument side demonstrated that tap water performed with the greatest efficacy for all types of instruments and cycle types. Using International standard methodology, different detergent classes had equivalence in cleaning efficacy. Cheaper detergents used in this study performed with similar efficacy to more expensive solutions. Findings emphasise the importance of validating the detergent (type and concentration) for each AWD.

ベッドパンウォッシャーによる洗浄・消毒の検証と有効な使用方法

ベッドパンウォッシャーによる洗浄・消毒の検証と有効な使用方法

Reproducible elimination of Clostridium difficile spores using a clinical area washer disinfector in 3 different health care sites

Following a Clostridium difficile infection outbreak, the Infection Prevention and Control team at our institution queried the risk of transmission via bedpans reprocessed in washer disinfectors (WDs). This study's objective was to determine the effectiveness of the mechanical action, detergent, and temperature on the eradication of C difficile spores in 1 type of WD model. Three types of reusable bedpans/pots were inoculated with sterile human feces that contained 1 × 10(7) CFU/mL C difficile spores. The 0.3 mL fecal-spore suspension was inoculated in sealed cryovials. These items were reprocessed using the longest wash cycle of WDs in 9 clinical units, and then tested for residual C difficile spores. The number of colonies on each replicate organism detection and counting plate was recorded after anaerobic incubation at 35°C for 48 hours, and the log reduction was calculated. All 9 WDs met the manufacturer's operational specifications. Forty-three (96%) of 45 bedpans had no viable spores (>5.9 log10C difficile spore reduction). Two bedpans had 1 to 2 spores remaining. Viable C difficile spores were isolated from all 9 cryovials. Results demonstrated that when operating the WD as stipulated, C difficile spores were satisfactorily eliminated from bedpan surfaces. Temperature alone was insufficient to kill C difficile spores. It also suggested the importance of staff training, machine maintenance, and WD purchase specifications.

The exploration of optimum cycle of automatic washer disinfector for endozime auto wash triple plus with advanced proteolytic action

Objective To explore optimum cycle of Automatic Washer Disinfector for endozime auto wash triple plus with advanced proteolytic action to ensure mechanical cleaning quality and improve safety of reusable medical instruments. Methods Visual inspection, STF cleaning efficacy monitoring test and Adenosine Triphosphate (ATP) test were used to verify cleaning quality of the newly updated No.4 automatic washer disinfector, and changed key parameters on weekly basis, such as pre-cleaning temperature, pre-cleaning time, detergent concentration, main cleaning temperature, and main flushing time, recorded cleaning results for three weeks: Group test of initial procedure, Group test 1 of optimization procedure and Group test 2 of optimization procedure. χ2 test was used to compare differences of the three groups and determine the optimum cycle. Results Group test 2 of optimization procedure had the highest visual inspection and ATP test qualification rate (both were 100.00%), and pass all the STF tests. Cleaning quality was significantly better than the other two groups, and the cycle made full use of the tested detergent. Conclusions Cycle parameters of cleaning machine have great impact on medical instruments cleaning quality; Specific consuming products need to be verified to determine the optimum cleaning cycle. Key words: Endozime auto wash triple plus with advanced proteolytic action; Automatic washer disinfector; Optimum cycle

Dental handpiece contamination: a proteomics and surface analysis approach

Dental handpieces (DHPs) become biofouled internally with patient derived material that is difficult to access for removal and inactivation. This study undertook a quantitative and qualitative investigation of protein contamination of internal components from three different types of DHP: the turbine, slow speed contra-angle and surgical. Eluates from the high speed turbine, low speed spray channels and surgical gear were assayed for protein using an orthophthaldehyde assay. Eluates concentrated by Amicon ultrafiltration were also analysed by SDS-PAGE, mass spectroscopy, Western blotting and ELISA. The surfaces of handpiece components were also investigated by SEM, EFSCAN and EDAX microscopy. Surgical gears contained highest levels of protein (403 μg), followed by low speed spray channels (17.7 μg) and the high speed turbine (<5 μg). Mass spectroscopy of surgical gears demonstrated mostly serum derived proteins. Decontamination of the DHPs using an automated washer disinfector and handpiece irrigator showed a significant reduction in residual protein levels.

Alkaline detergent combined with a routine ward bedpan washer disinfector cycle eradicates Clostridium difficile spores from the surface of plastic bedpans

The cleaning efficiency of a ward bedpan washer disinfector was evaluated using various cycle parameters and detergent to determine which conditions could effectively eliminate Clostridium difficile spores from the surface of bedpans. Results revealed that the regular intensive cycle with thermal conditions of 85°C for 60 seconds plus the addition of an alkaline detergent was sufficient to eradicate C difficile spores. However, these thermal conditions alone, without detergent, were not adequate.

Summary of: A quantitative assessment of residual protein levels on dental instruments reprocessed by manual, ultrasonic and automated cleaning methods

Objective To assess residual protein on dental instruments cleaned in general dental practice by manual, manual plus ultrasonic and automated washer disinfector (AWD) processes. Design and setting Instruments submitted by 30 dental surgeries in the South West of England. Subjects (materials) and methods Instruments analysed were matrix bands, associated retaining clips, diamond and stainless steel burs, extraction forceps and hand scalers. Each instrument was visually assessed under magnification for residual debris. Residual protein was extracted by immersion in detergent and sonication. A collection of used but uncleaned instruments of each type (n = 177) was also analysed for adherent protein using ophthalaldehyde/N–acetylcysteine reagent. Main outcome measures Residual protein levels allowed comparisons to be made on the effectiveness of different cleaning processes. Results One thousand, three hundred and four instruments were analysed. Observational data demonstrated several shortcomings in cleaning chemistries and operation of the AWD. For uncleaned instruments, median residual protein levels ranged from 0.4 μg (stainless steel burs) to 462 μg (extraction forceps). Following manual washing, median protein levels ranged from 0.3-78 μg; for manual plus ultrasonic washing, levels ranged from 9-39 μg and AWD levels ranged from 0.3-27 μg. Manual washing combined with ultrasonic cleaning was significantly less effective than the other two processes (p <0.008). AWDs reduced the variability in the cleaning process. No correlation was found between visual scoring and residual protein determination. Conclusion(s) There was a wide variation in residual protein levels both within and between different methods and instruments and this underlines the complexity of this process.

A quantitative assessment of residual protein levels on dental instruments reprocessed by manual, ultrasonic and automated cleaning methods

To assess residual protein on dental instruments cleaned in general dental practice by manual, manual plus ultrasonic and automated washer disinfector (AWD) processes. Instruments submitted by 30 dental surgeries in the South West of England. Instruments analysed were matrix bands, associated retaining clips, diamond and stainless steel burs, extraction forceps and hand scalers. Each instrument was visually assessed under magnification for residual debris. Residual protein was extracted by immersion in detergent and sonication. A collection of used but uncleaned instruments of each type (n = 177) was also analysed for adherent protein using ophthalaldehyde/N-acetylcysteine reagent. Residual protein levels allowed comparisons to be made on the effectiveness of different cleaning processes. One thousand, three hundred and four instruments were analysed. Observational data demonstrated several shortcomings in cleaning chemistries and operation of the AWD. For uncleaned instruments, median residual protein levels ranged from 0.4 μg (stainless steel burs) to 462 μg (extraction forceps). Following manual washing, median protein levels ranged from 0.3-78 μg; for manual plus ultrasonic washing, levels ranged from 9-39 μg and AWD levels ranged from 0.3-27 μg. Manual washing combined with ultrasonic cleaning was significantly less effective than the other two processes (p <0.008). AWDs reduced the variability in the cleaning process. No correlation was found between visual scoring and residual protein determination. There was a wide variation in residual protein levels both within and between different methods and instruments and this underlines the complexity of this process.

Decontamination of viableStreptococcus mutansfrom orthodontic tungsten carbide debonding burs. Anin vitromicrobiological study

To investigate the effectiveness of currently recommended decontamination procedures on tungsten carbide debonding burs (TCDBs). In vitro microbiological study. St George's Hospital NHS Trust, UK. A total of 240 extracted tooth surfaces were bonded with orthodontic brackets, debonded to leave residual composite and artificially contaminated with Streptococcus mutans. Sterilized TCDBs in a slow handpiece were used to remove this composite before random allocation into one of six different decontamination groups of 40 burs each. These included a control group that was not decontaminated and a further five that underwent different methods of presterilization cleaning within the decontamination process (none, manual, ultrasonic, washer disinfector and enzyme soak) followed by sterilization in a vacuum phase autoclave at 134 degrees C for 3 min. The burs were placed in brain heart infusion (BHI) broths, incubated for 48 h. Following this the broths were inspected for turbidity and microbiological analysis was carried out to detect viable bacterial growth. Data were analysed using the Kruskal-Wallis test for single ordered data. S. mutans was recovered from 39 out of 40 burs in the control group and no burs from the decontamination groups, which was statistically significant (P = 0.001). No differences were found between decontamination groups (P = 0.271). However, skin flora contamination was noted in 17 broths. The five methods of decontaminating TCDBs investigated in this study were effective in removing viable S. mutans. Other investigations are required to determine if TCDBs can be successfully cleaned of blood and protein residue prior reuse.