Disinfection Methods Research Articles

The Effect of Five Disinfection Methods on Candida albicans-Infected Chair-Side Soft Liners: A Comparative In Vitro Study

Background: Soft-liners, particularly used for patients with poor hygiene habits, can become a favorable environment for the aggregation of microorganisms. Therefore, disinfection is considered a critical process for preserving the health of oral mucosa. This study aimed to determine the antifungal efficacy of five different disinfectant methods on silicone resilient lining materials. Material and Method: A total of 60 test samples were prepared and inoculated with 2 ml of Candida solution and incubated for 2 hours. The inoculated specimens were then randomly divided into six groups (n=10): Control group, 0.5% sodium hypochlorite (NaOCl) group, Corega® denture cleansing tablet group, microwave water group, diode laser group, and 4% iodine solution group. A swab was taken from the surfaces of the soft-liner discs in each group, planted on aerobic culture media, and the colonies were counted separately for each treatment. Results: A significant difference (p < 0.05) in inhibiting the growth of Candida albicans was observed with all five types of disinfection methods compared to the control group. Conclusion: According to the results, the iodine group and the laser group demonstrated the best disinfection effects, respectively.

Transformation behavior and toxicity assessment of beaytlmethodeyammonNium chbride (BAC-12) disinfectant during hospital wastewater treatment.

This work focused on the transformation behavior of the emerging beaytlmethodeyammonium chbride (BAC-12) disinfectant existed in the treatment of medical sewage during its disinfection treatment. The degradation ability of ozone (O3) to BAC-12 was the best, followed by UV/NaOCl, UV, and NaOCl. The enhancement of BAC-12 in UV/NaOCl system is caused by the combined effect of UV photolysis, reactive chlorine species (RCS), and •OH. The transformation products of BAC-12 in the disinfection treatment were detected, and the chemical structure of products was rationalized by frontier molecular orbital and transition state theory methodologies. According to the ecological structure-activity relationship (ECOSAR) assessment, the intermediates of BAC-12 in UV, NaOCl, and UV/NaOCl treatments had lower half lethal concentration (LC50) and chronic toxicity (ChV) values with a higher ecotoxicity than BAC-12. O3 disinfection treatment of these toxic intermediates can significantly reduce the toxicity of the BAC-12 solution. This work provides necessary information on the potential environmental risks of BAC-12 arising from different disinfection methods in the treatment of medical wastewater.

Analysis of domestic wastewater disinfection methods using chlorine dioxide and sodium hypochlorite

Pollution of surface water bodies poses a threat to the environment and human health. After improper wastewater treatment at municipal enterprises, mineral and organic pollutants gradually accumulate in water bodies, which in turn worsens the ecological situation and leads to outbreaks of infectious diseases. The reason for periodic violations of the operation of treatment plants is the imperfection of the technological regime. Therefore, there is an urgent need to improve the efficiency of existing biological treatment facilities by means of measures that ensure compliance with environmental requirements for urban wastewater treatment. Chlorine or its compounds are used as disinfectants: chlorine dioxide, sodium hypochlorite, calcium hypochlorite and others. Methods of wastewater disinfection using chlorine dioxide and sodium hypochlorite are considered in the work. The main advantages and problems of using these methods in comparison with the traditional use of chlorine are highlighted.

Bactericidal efficacy of low dose gaseous ozone against clinically relevant multidrug-resistant bacteria

IntroductionHealthcare-associated infections (HAIs) pose a significant challenge in acute care hospitals, particularly in intensive care units, due to persistent environmental contamination despite existing disinfection protocols and manual cleaning methods. Current disinfection methods are labor-intensive and often ineffective against multidrug-resistant (MDR) pathogens, highlighting the need for new, automated, hands-free approaches.MethodsThis study evaluates the bactericidal efficacy of low concentrations of gaseous ozone (5 ppm) against clinically relevant and often MDR bacteria under various concentrations, contact times, temperatures, and environmental conditions.ResultsWe observed a 3 log10-fold reduction in Escherichia coli and Salmonella Typhimurium and a 1–2 log10-fold reduction in group A Streptococcus and methicillin-resistant Staphylococcus aureus upon ozone exposure. The bactericidal effect was dose-dependent, with no significant difference between single and repeated exposures. Environmental conditions such as temperature and humidity had minimal impact on low-dose ozone efficacy, with slightly improved bacterial killing at colder temperatures and higher humidity levels. Gaseous ozone also showed significant bactericidal activity against the broad range of Gram-positive and -negative MDR clinical isolates.DiscussionThese findings highlight the potential of low-dose gaseous ozone as a versatile, effective, and hands-free disinfectant for healthcare and other settings. Further research is needed to establish long-term safety and efficacy guidelines for its use in occupied spaces and to explore potential synergy with other contemporary disinfection strategies.

Local Electric Field-Incorporated In-Situ Copper Ions Eliminating Pathogens and Antibiotic Resistance Genes in Drinking Water

Background/Objectives: Pathogen inactivation and harmful gene destruction from water just before drinking is the last line of defense to protect people from waterborne diseases. However, commonly used disinfection methods, such as chlorination, ultraviolet irradiation, and membrane filtration, experience several challenges such as continuous chemical dosing, the spread of antibiotic resistance genes (ARGs), and intensive energy consumption. Methods: Here, we perform a simultaneous elimination of pathogens and ARGs in drinking water using local electric fields and in-situ generated trace copper ions (LEF-Cu) without external chemical dosing. A 100-μm thin copper wire placed in the center of a household water pipe can generate local electric fields and trace copper ions near its surface after an external low voltage is applied. Results: The local electric field rapidly damages the outer structure of microorganisms through electroporation, and the trace copper ions can effectively permeate the electroporated microorganisms, successfully damaging their nucleic acids. The LEF-Cu disinfection system achieved complete inactivation (>6 log removal) of Escherichia coli O157:H7, Pseudomonas aeruginosa PAO1, and bacteriophage MS2 in drinking water at 2 V for 2 min, with low energy consumption (10−2 kWh/m3). Meanwhile, the system effectively damages both intracellular (0.54~0.64 log) and extracellular (0.5~1.09 log) ARGs and blocks horizontal gene transfer. Conclusions: LEF-Cu disinfection holds promise for preventing horizontal gene transfer and providing safe drinking water for household applications.

Preservation of minimally processed carrots using the combination of ultrasound and mild heat ascorbic acid

Ultrasound (US) in combination with chemical disinfectants is an efficient and cost-effective hurdle technology for disinfecting minimally processed produce (MPP). However, the demand for non-chemical disinfection methods is increasing. In addition, chemical methods have been ineffective in simultaneously improving the physiological properties and inactivating pathogens in MPP. In this study, a novel and safe method called mild heat ascorbic acid (MHAsA; 1 % AsA at 50 °C) was combined with US to process minimally processed carrots. Physiological properties and microbial inactivation efficacy were analyzed during the storage period (0–5 days). The findings indicated that US-MHAsA induced the highest levels of antioxidant enzymes (superoxide dismutase and catalase) activities and accelerated the glutathione-ascorbate cycle, resulting in lower reactive oxygen species (ROS) and malondialdehyde content compared to US and MHAsA. The efficacy of US-MHAsA in inactivating phenylalanine lyase, the initial enzyme in the lignin synthesis process, was lower than that of US. On the other hand, its ability to inactivate cinnamyl alcohol dehydrogenase, the final enzyme in the process, was better than that of both US and MHAsA. However, there were no significant differences in lignin content among the three groups. The inactivation efficacy against enzymes (polyphenol oxidase and peroxidase) involved in browning was consistent across the three treatments. Analysis of the disinfection efficacy against Escherichia coli O157:H7 and Salmonella Typhimurium revealed that US-MHAsA achieved the lowest cross-contamination incidence (10–12 %) during washing, which was significantly lower than the incidence achieved by US (75–82 %). During the period from day 0 to day 5, two pathogens on carrots in the control group increased from 6.25 to 6.64 log CFU/g, while the lowest counts were observed in the US-MHAsA group, decreasing from 4.44 to 3.74 log CFU/g. However, the counts in the US group increased from 5.22 to 6.32 log CFU/g, and the counts at day 5 were not significantly lower than the control. These findings indicate that US-MHAsA is a novel hurdle technology that effectively reduces the risk of pathogen contamination and enhances the ability of MPP to scavenge ROS.

“Nano knife” for efficient piezocatalytic inactivation of amoeba spores and their intracellular bacteria: Synergetic effect between physical damage and chemical oxidation

Microbial interactions between infectious agents severely interfere with the disinfection process, and current disinfection methods are unable to effectively inactivate intracellular pathogens, posing a new threat to drinking water safety. In this study, we first reported the high efficiency of piezocatalysis in inactivating amoebae and their intracellular bacteria. Results showed that the inactivation rates of the MoS2/rGO piezocatalytic system for amoebic spores and their intracellular bacteria were 4.18 and 5.02-log, respectively, within 180min. Based on scavenger studies and ESR tests, the efficient inactivation of pathogens can be attributed to the generation of reactive oxygen species (ROS), and different pathogens exhibit varying tolerances to distinct ROS. Moreover, TEM analysis revealed that the sharp edge of MoS2/rGO was conducive to the physical cutting of amoeba's cell wall and membrane, promoting the attack of ROS and ensuring a more thorough deactivation. Additionally, the intracellular ROS produced by amoebae is not only conducive to the inactivation of amoebae but also the main reason for the inactivation of bacteria in spores. This study provides a new solution for the inactivation of amoeba spores and their intracellular bacteria and emphasizes the high efficiency of the synergistic effect of physical damage and chemical oxidation.

Insights on bacteria inactivation in water by cold plasma: Effect of water matrix and pulsed plasmas waveform on physicochemical water properties, species formation and inactivation efficiency of Escherichia coli

This study investigates the inactivation of Escherichia coli (E. coli) using pulsed dielectric barrier discharges (DBDs) powered by high-voltage nanosecond and/or microsecond pulses to establish optimal operational conditions. The effects of pulse voltage waveform and water matrix (distilled vs. tap water) were evaluated in terms of inactivation efficiency and energy consumption, along with the generation of reactive oxygen and nitrogen species (RONS). Complete E. coli inactivation (9-log CFU/ml) in distilled water was achieved within 20 min of nanopulsed-DBD treatment, coinciding with rapid acidification, while in tap water, 90 min was required for complete inactivation. Interestingly, at treatment times with similar pH levels between water types, E. coli inactivation was more effective in tap water. Ozone concentrations showed the most significant difference, being ∼6 times higher in distilled water (10.3 mg/L) than in tap water (1.7 mg/L). Although distilled and tap water had similar concentrations of short- and long-lived plasma species, the differing inactivation efficiencies indicate a synergistic effect between pH reduction and reactive species in impairing E. coli functionality. Micropulsed-DBD led to increased concentration of plasma species, faster acidification and inactivation in tap water (complete inactivation within 8 min), but at significantly higher electrical energy per order (56.9 kWh/m3 compared to 17.4 kWh/m3 for nanopulsed-DBD). The lowest energy per order was recorded for nanopulsed-DBD in distilled water, at 3.8 kWh/m³, highlighting pulsed-DBD plasma as a safe and energy-efficient method for water disinfection. This study offers valuable insights into using an innovative, sustainable plasma-based approach for bacterial inactivation.

Synergistic interplay of Z-type CuNb2O6/KCNNT heterojunction and molecular oxygen accelerated Cu(II)/Cu(I) cycle in visible light photocatalytic-Fenton-like reaction for efficient bacteria removal

Global clean water shortages, exacerbated by microbial contamination, pose significant challenges. Traditional disinfection methods have limitations, creating demand for cost-effective and sustainable alternatives. This study presents a novel heterogeneous photocatalytic-Fenton-like disinfection system (CNO/KCNNT/H2O2/Vis/Air) that leverages a Z-type heterojunction catalyst composed of CuNb2O6 (CNO) and potassium-doped carbon nitride nanotubes (KCNNT). The design facilitates efficient charge carrier transfer and separation, enhancing Cu(II)/Cu(I) cycling and H2O2 activation to generate reactive oxygen species (·OH and ·O2–), which enable rapid and effective disinfection. When exposed to visible light, the system achieved a notable 7-log reduction of Acinetobacter baumannii within 15 min, with a kinetic rate constant of 1.73 min−1, demonstrating a 4.1-fold and 4.8-fold enhancement over KCNNT (0.42 min−1) and CuNb2O6 (0.36 min−1), respectively. Air bubbling provided sufficient dissolved oxygen, with CuNb2O6 and KCNNT exhibiting effective adsorption for H2O2 and O2, respectively. KCNNT favors O2 activation to produce ·O2–, which efficiently accelerates Cu valence cycling and H2O2 activation. Mechanistic insights into ROS generation and activity were elucidated through quenching experiments, EPR analysis, ROS quantification, DFT calculations, and XPS. Additionally, the catalyst demonstrated excellent stability, reusability, and resistance to interference from coexisting ions in repeated experiments. This work advances the understanding of Cu-based semiconductor photocatalytic-Fenton-like systems, providing a promising approach for sustainable water disinfection.

Evaluation of plasma activated liquids for the elimination of mixed species biofilms within endoscopic working channels.

The use of reusable flexible endoscopes has increased dramatically over the past decade, however despite improvements in endoscope reprocessing, the continued emergence of endoscopy-associated outbreaks as a result of multi-drug resistant bacteria has highlighted the need for a new approach to disinfection. Here,the use of plasma activated liquids (PALs) for the elimination of mixed species biofilm contamination within the working channels of endoscopes was evaluated. Cold atmospheric pressure plasma was used to chemically activate water and a commercially available pH buffered peracetic acid to create PALs. Polytetrafluoroethylene endoscope surrogate test pieces were contaminated with clinically relevant mixed species biofilms. The efficacy of PALs for the decontamination of narrow lumens was compared against the commercial disinfectant. Plasma activation was found to increase the antibiofilm capabilities of pH buffered peracetic acid by introducing reactive chemical species into the solution. Disinfection of endoscopic test pieces with plasma activated disinfectant (PAD) resulted in a 7.30 log10 reduction of biofilm contamination in 5min, surpassing the 4.39 log10 reduction observed with the currently used endoscope disinfection method. PAD also resulted in reduced regrowth and recolonization of the surface of the endoscopic test pieces. Minimal changes to the surface morphology and composition were observed following exposure to PAD in comparison to the commercial disinfectant, suggesting the developed approach is no more aggressive than current disinfection approaches.

Operating room sterilization and disinfection methods

Operating room sterilization and disinfection methods

Comparison of ultraviolet C light and isopropyl alcohol for the disinfection of cellular phones in a paediatric intensive care unit setting.

A considerable proportion of cellular phones (cell phones) used by healthcare workers (HCWs) have been shown to be contaminated with pathogenic micro-organisms, making these devices reservoirs to infect susceptible patients. Although many units have well-defined infection control protocols, methods for the decontamination of cell phones are scarce. To compare the efficacy of ultraviolet C (UVC) light with that of 70% isopropyl alcohol in disinfecting cell phones used by HCWs in a paediatric intensive care unit (ICU). A randomised controlled study in a paediatric ICU setting was conducted. Cell phones of HCWs or other personnel entering the ICU were swabbed prior to and after decontamination with either the 70% isopropyl alcohol or UVC light method. The reduction ratio of colony-forming units (CFUs) before and after intervention was analysed using the Mann-Whitney U-test. In addition, the effectiveness of the disinfection methods was compared using the Wilcoxon signed-rank paired test. A total of 74 cell phones were acquired from HCWs working in the paediatric ICU. After excluding 5, 69 samples were therefore available for statistical analysis, with 34 samples subjected to disinfection using 70% isopropyl alcohol-based swabs and 35 samples treated with UVC light disinfection. Disinfection with 70% isopropyl alcohol (z=5.16; p<0.000001) and with UVC light (z=3.28; p<0.005) were individually statistically significantly effective in reducing CFUs. The CFU reduction ratio indicated that disinfection using a 70% isopropyl alcohol solution was 67% more effective than UVC light disinfection (Mann-Whitney U-test score 968; p<0.001). Although both 70% isopropyl alcohol and UVC light disinfection effectively reduced CFUs following decontamination, 70% isopropyl alcohol was determined to be much more effective.

Efficacy of different disinfecting methods for contact lenses against Acanthamoeba castellanii

PurposeTo analyze the efficacy of different disinfecting methods for contact lenses (CL) against Acanthamoeba castellanii (AC) using quantitative PCR (qPCR) based on RNA detection. MethodsThree CL materials: rigid gas permeable (RGP), hydrogel (Hy), and silicone hydrogel (SiHy), were contaminated with 1x105 amoebae/ml and incubated for 24 h at 30 °C. After contamination, pre-cleaning steps were performed before using four maintenance solutions based on hydrogen peroxide (HP), sodium hypochlorite (SH), povidone-iodine (PI), and a multipurpose solution (MS). The pre-cleaning steps involved using a cleaner (20 % isopropyl alcohol) and rinsing the CL. Disinfection systems 1 and 2 involved no cleaner and rinsed the CL with tap water or saline solution, respectively. Systems 3 and 4 included a cleaner and rinsed with tap water or saline, respectively. After cleaning, A. castellanii was extracted and stored for qPCR analysis, using Hsp70 and TPBF genes to detect RNA A. castellanii. Results were presented as the percentage of positives or negatives (presence or absence of amoebae), with a p-value < 0.05 considered statistically significant. ResultsDisinfection system 1 with MS resulted in 56 % positives for RGP lenses and 100 % positives for both hydrogel materials. When MS was combined with a cleaner, 12.5 % positives were found for SiHy and 100 % negatives for Hy and RGP lenses (p < 0.05). PI solution alone yielded 38 % and 12 % positives for hydrogel and silicone hydrogel lenses, respectively, but was 100 % effective when combined with a cleaner. HP and SH, whether combined with a cleaner or not, were effective against AC for all CL materials, except HP without a cleaner for Hy lenses. ConclusionAll disinfection methods showed some efficacy against Acanthamoeba on any CL material. The most effective solutions were those based on hydrogen peroxide and sodium hypochlorite. Using a cleaner enhanced the final disinfecting efficacy, especially with the multipurpose solution.

Evaluation of the microbial contamination of the audiological diagnostic equipment and, their current disinfection techniques

BackgroundThe study aims to investigate the microbial contamination of commonly used audiological diagnostic equipment and to evaluate the effectiveness of existing disinfection methods in audiological clinics. MethodsHospitals with fully equipped audiology clinics in Istanbul were included in the study. Various audiological diagnostic devices, such as Pure Tone Audiometer, Tympanometer, and Auditory Brainstem Response (ABR), were examined. The study also investigated the disinfection practices in hospitals. A total of 60 swab samples were collected from the stimulus button on the audiometer, patient response switch, supraaural headphone cushion, bone conduction headphone (bone vibrator), and disinfected probe tips used in the Tympanometer and ABR. ResultsBacterial growth was observed on 40% of the analyzed plates, with 11.66% showing two different types of bacterial growth. Staphylococcaceae family were the most common bacteria identified. Other bacteria included Pseudomonas putida, Panteoa spp, Micrococcus luteus, Corynebacterium spp, and Bacillus spp. The highest bacterial growth occurred on the supraaural headphone cushion and bone vibrator. ConclusionsThe study highlights the presence of various bacteria on audiological diagnostic equipment, emphasizing Staphylococcus species as predominant. Current disinfection practices, particularly for supraural headphones and bone vibrators, were found to be inadequate, potentially posing risks for infections. The study suggests the need for disinfection protocols, particularly for frequently touched devices, to ensure patient safety in clinics.

Exploring the Microbiome of Mobile Devices: Implications for Public Health and Hygiene

This study, which examined the diversity of microorganisms found on mobile phones, took a novel approach by identifying pathogenic microbes on phone users within different age groups. The study also aimed to test the effectiveness of a simple disinfection method using 70% sterile alcohol pads. Samples were collected using sterile cotton tip applicators and transport broth media before and after disinfection. The samples were cultured and incubated on Muller Hinton agar petri plates at 32 degrees Celsius for 48 hours. The isolated microbes were identified based on their morphological characteristics, gram-stain test, and biochemical analysis. The survey, conducted to determine the frequency of mobile phone usage and factors contributing to microbial contamination, revealed significant findings. Participants from two villages were surveyed using a structured questionnaire. The sample size of participants was generated using a sample size calculator. Two participants from each age group per village were selected randomly for microbial sample collection from their mobile phones using R Studio software. The results showed that older adults' mobile phones were more contaminated than younger adults and adolescents, providing valuable insights. The frequency of usage and hygiene did not determine the total viable count of pathogenic microbes found, challenging existing assumptions. The study also found that disinfection using 70% sterile alcohol pads was 76% effective in reducing microbial contamination.

A socioeconomic and cost benefit analysis of Tropical Race 4 (TR4) prevention methods among banana producers in Colombia.

The global banana industry faces a significant threat from Fusarium oxysporum f. sp. cubense Tropical Race 4 (TR4). While prior research has concentrated on TR4's dissemination, reproductive conditions, and resistant banana varieties, this study employs a socioeconomic and cost-benefit analysis to explore the vulnerability of banana producers to TR4 in Colombia. It assesses the financial viability of current monitoring strategies and estimates potential losses in the event of TR4 spreading within the study area. Interviews were conducted with producers and key stakeholders in Colombia's top two banana-producing departments, Antioquia and Magdalena. The findings reveal that farming systems are highly vulnerable to TR4, particularly due to the prevalent use of corms. Producers employ preventive measures such as cement paths, fences, disinfecting stations, and footbaths to counteract TR4's spread. A cost-benefit analysis indicates that the benefits of these prevention methods significantly outweigh the associated costs, with a net present value of implementing prevention strategies per hectare of $95,389 USD and $112,527 USD in Magdalena and Antioquia and a benefit-cost ratio of 3.1 and 4.2, respectively. Considering the substantial impact TR4 could have in Colombia if it becomes more widespread, we recommend widespread adoption of preventive measures, including the construction and utilization of cement paths and disinfectant methods on all banana farms. Additionally, to enhance awareness and early detection, we propose leveraging technology, such as mobile applications (apps) and chat groups, to empower farmers in identifying and preventing the spread of TR4.

Global transcriptional response of Pseudomonas aeruginosa to UVA radiation.

Ultraviolet A (UVA) radiation is the major fraction of UV radiation reaching the Earth's surface. Its harmful effects on microorganisms, due mainly to oxidative damage, have been exploited for development of natural solar and commercial UVA-based disinfection methods. In this work, the global transcriptional response of Pseudomonas aeruginosa exposed to ultraviolet A (UVA) radiation was analyzed. To conduct this study, we analyzed the whole transcriptome of the PAO1 strain grown to logarithmic phase under sublethal doses of UVA or in the dark. We found that a total of 298 genes responded to UVA with a change of at least two-fold (5.36% of the total P. aeruginosa genome), and showed equal amount of induced and repressed genes. An important fraction of the induced genes were involved in the response to DNA damage and included induction of SOS, prophage and pyocins genes. The results presented in this study suggest that one of the main UVA targets are proteins carrying [Fe-S] clusters since several genes involved in the processes of synthesis, trafficking and assembly of these structures were upregulated. The management of intracellular iron levels also seems to be a robust response to this stress factor. The strong induction of genes involved in denitrification suggest that this pathway and/or reactive nitrogen species such as nitric oxide could have a role in the response to this radiation. Regarding the down-regulated genes, we found many involved in the biosynthesis of PQS, a quorum-sensing signal molecule with a possible role as endogenous photosensitizer.

Cancer incidence associations with drinking water arsenic levels and disinfection methods in Maine, USA.

Maine is a largely rural state where nearly half of the population uses drinking water from private wells. Arsenic (As) is present in some Maine groundwater, has been linked to cancer, and a lack of testing and treatment may expose people with private wells to elevated As levels. Disinfection byproducts (DBPs) include known and suspected carcinogens that form when chlorine or chloramines are added to water. People served by public water systems may be exposed to elevated levels of regulated DBPs such as trihalomethanes and haloacetic acids associated with chlorine and/or unregulated nitrogenous DBPs, or N-DBPs, such as nitrite and N-nitrosodimethylamine associated with chloramines. Contrary to initial expectations, there were no significant associations between median town As in well water and bladder, lung, kidney, or skin cancer incidence. Furthermore, bladder, melanoma, and other skin cancer incidence rates were negatively correlated with the percent of the town population using private wells. Analysis of cancer incidence associated with chlorine and chloramine disinfection showed elevated melanoma, and other skin cancer with chloramine use and elevated bladder and non-melanoma skin cancer with chlorine use compared to the no disinfectant case. We recommend more research on the links between disinfectant use and cancer.

Disinfection in Archives—A Short Review of the Sustainable Approaches and Green Perspectives of Using Radiation for Mass Disinfection

The conservation of the immense archival heritage of a country like Italy presents scholars with the enormous challenge of finding techniques and procedures that enable rapid and large-scale interventions, especially in cases of biodeterioration. The volume of material to be preserved and often the inadequacy of the storage conditions constitute crucial factors that promote microbial growth on substrates such as paper, leather, and parchment. These materials serve as primary sources of sustenance for fungi and bacteria which can infect the collections, and so it is frequently necessary to adopt chemical mass-disinfection treatments. These treatments are often expensive, polluting, and hazardous to the assets, the operators, and the environment. The use of ionizing radiation can provide an environmentally sustainable alternative to the traditional mass disinfection treatments of library and archive materials, which currently involve chemical agents (such as ethylene oxide) that impact the environment and human health. The use of such chemicals is increasingly subject to stringent restrictions. In this work, we report and discuss the advantages and disadvantages of physical disinfection methods, focusing on the use of radiation for disinfection treatments and their effects.

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.