Effect of UV-C light or hydrogen peroxide wipes on the inactivation of methicillin-resistant Staphylococcus aureus, Clostridium difficile spores and norovirus surrogate

Ultraviolet-C-based sanitization is a cost-effective option for hospitals to manage health care-associated infection risks from high touch mobile phones

Mobile phones have become essential tools for health care workers around the world, but as high touch surfaces, they can harbor microorganisms that pose infection risks to patients and staff. As their use in hospitals increases, hospital managers must introduce measures to sanitize mobile phones and reduce risks of health care-associated infections. But such measures can involve substantial costs. Our objective in this paper was to consider two mobile phone risk mitigation strategies that managers of a hypothetical hospital could implement and determine which involves the lowest cost. The first strategy required all staff to sanitize their hands after every contact with a mobile phone. The second involved the hospital investing in ultraviolet-C-based mobile phone sanitization devices that allowed staff to decontaminate their mobile phones after every use. We assessed each intervention on material and opportunity costs assuming both achieved an equivalent reduction in microbe transmission within the hospital. We found that ultraviolet-C devices were the most cost-effective intervention, with median costs of approximately AUD360 per bed per year compared to AUD965 using hand hygiene protocols. Our results imply that a 200-bed hospital could potentially save AUD1-1.4 million over 10 years by investing in germicidal ultraviolet-C phone sanitizers rather than relying solely on hand hygiene protocols.

Synergistic effects of a sequential recirculation electrochemical system combined with low-cost UV-LEDs on the gram-negative bacteria inactivation

In this work, an electrochemical system combined with low-cost UV-LEDs was implemented for the inactivation of Escherichia coli and Pseudomonas aeruginosa. The individual elimination of these bacteria was followed by plate counting and flow cytometry, as complementary techniques to establish the cell inactivation and non-viability, respectively. The contribution of the different parts of the disinfection system (anode, cathode, and light) was determined. In addition, the efficiency of the UV-LEDs/GDE/DSA system in the disinfection of an irrigation water sample was studied. It was found that the combination of the electrochemical system with UV-LEDs was highly synergistic (φ > 7), having low electric energy consumptions per order of magnitude (EEO: 1.13 × 10-2 and 1.55 × 10-2 kWh/m3 order). Moreover, some differences in the inactivation kinetics and synergy between E. coli and P. aeruginosa were observed and linked to the structural/morphological characteristics of the two bacteria. Remarkably, the electrochemical system combined with low-cost UV-LEDs inactivated both target microorganisms after only 2 min of treatment. The flow cytometry analyses evidenced the damage to the cell membrane of the bacteria by the simultaneous and synergistic action of the electrogenerated H2O2 and active chlorine species (ACS), plus the attacks of photo-generated reactive oxygen species. This synergistic combination in the UV-LEDs/GDE/DSA system demonstrated remarkable efficiency in the disinfection of an irrigation water sample, achieving the elimination of culturable bacteria in 45 min of treatment. The results of this research demonstrated the capacity and great potential of an easy combination of electrochemistry with UV-LEDs as an alternative system for the elimination of gram-negative bacteria in water.

Ultraviolet (UV-C) Light Systems for the Inactivation of Feline Calicivirus and Tulane Virus in Model Fluid Foods

Conventional UV-C (254 nm) inactivation technologies have limitations and potential operator-safety risk. To overcome these disadvantages, novel UV-C light-emitting diodes (LED) are developed and investigated for their performance. This study aimed to determine the inactivation of human norovirus (HuNoV) surrogates, Tulane virus (TV), and feline calicivirus (FCV-F9), by UV-C (254 nm) in comparison to UV-C LED (279 nm) in phosphate-buffered saline (PBS) and coconut water (CW). Five-hundred microliters of FCV-F9 (~ 5 log plaque forming units (PFU)/mL) or TV (~ 6 log PFU/mL) were added to 4.5 mL PBS or CW in continuously stirred glass beakers and exposed to 254 nm UV-C for 0 up to 15 min (maximum dosage of 33.89 mJ/cm2) or 279 nm UV-C LED for 0 up to 2.5 min (maximum dosage of 7.03 mJ/cm2). Recovered viruses were assayed in duplicate from each treatment replicated thrice. Mixed model analysis of variance was used for data analysis. Significantly lower D10 values were obtained in PBS and CW (p ≤ 0.05) for both tested viruses using UV-C LED (279 nm) where FCV-F9 showed D10 values of 7.08 ± 1.75 mJ/cm2 and 3.75 ± 0.11 mJ/cm2, while using UV-C (254 nm) showed D10 values of 13.81 ± 0.40 mJ/cm2 and 6.43 ± 0.44 mJ/cm2 in PBS and CW, respectively. Similarly, lower D10 values were obtained for TV of 3.91 ± 1.03 mJ/cm2 and 4.26 ± 1.02 mJ/cm2 with 279 nm UV-C LED and were 18.76 ± 3.16 mJ/cm2 and 10.21 ± 1.48 mJ/cm2 with 254 nm UV-C in PBS and CW, respectively. Viral resistance to these treatments was fluid-matrix dependent. These findings indicate that use of 279 nm UV-C LED is more effective in inactivating HuNoV surrogates than conventional 254 nm UV-C in the tested fluids.

UVC Box: An Effective Way to Quickly Decontaminate Healthcare Facilities' Wheelchairs

Disinfection in the hospital environment remains challenging, especially for wide and structurally complex objects such as beds or wheelchairs. Indeed, the regular disinfection of these objects with chemicals is manually carried out by healthcare workers and is fastidious and time-consuming. Alternative antibacterial techniques were thus proposed in the past decades, including the use of naturally antimicrobial UVC. Here, the antibacterial efficiency of a large UVC box built to accommodate wheelchairs was investigated through testing bacterial burden reductions on various parts of a wheelchair, with various support types and with several treatment durations. The results demonstrate a time-dependent antibacterial effect, with a strong burden reduction at only five minutes of treatment (>3-log median reduction in Escherichia coli and Staphylococcus epidermidis). The UVC flux and residual bacterial burden both significantly varied depending on the spatial location on the wheelchair. However, the nature of the support impacted the antibacterial efficiency even more, with residual bacterial burdens being the lowest on rigid materials (steel, plastics) and being the highest on tissue. On metallic samples, the nature of the alloy and surface treatment had various impacts on the antibacterial efficiency of the UVC. This study highlights the efficiency of the tested UVC box to efficiently and quickly decontaminate complex objects such as wheelchairs, but also gives rise to the warning to focus on rigid materials and avoid porous materials in the conception of objects, so as to ensure the efficiency of UVC decontamination.

Analysis of a UV photocatalytic oxidation-based disinfection system for hydroxyl radicals, negative air ions generation and their impact on inactivation of pathogenic micro-organisms

This work presents a large-scale surface disinfection system, which has a unique lantern arrangement of ultraviolet-C (UV-C) light (254 nm) in conjunction with nanotechnology in a protective biosafety environment. Shadow regions are best dealt in this system by the generation of hydroxyl radicals (•OH) and negative air ions at sites where UV light cannot penetrate. More than 35 000 negative air ions/cm3 along with •OH were produced continuously in the disinfection chamber through the advanced photocatalytic oxidation process [UV-C + titanium dioxide (TiO2)]. The arrangement has been made to provide an optimized UV irradiation (∼2 mW/cm2) throughout the disinfection system. In order to distinguish between effects arising from (i) the action of UV dose alone and (ii) the action of UV dose along with •OH and negative air ions, E. coli and P. aeruginosa were chosen for bacterial testing and two interventions were made. The first intervention involved placing only UV lamps in the disinfection chamber to see the effect of only UV dose on bacterial inactivation efficiency. The second intervention involved placing the TiO2 nanoparticle coated aluminum plates along with UV lamps; this allows for the generation of negative air ions and •OH inside the disinfection chamber and enhanced bacterial inactivation efficiency. More than 95% bacterial inactivation efficiency has been reported in the case of UV-C + TiO2 compared to only 77% in UV only at the same time interval (90 s).

Efficacy of a bioburden reduction intervention on mobile phones of critical care nurses

BACKGROUND

Current literature identifies mobile phones of staff as potential vectors for hospital-acquired infection.

METHODS

A pre-post, quasi-experimental study was conducted in a 20 bed intensive care unit (ICU). Surface bioburden of personal and shared mobile phones was estimated with a luminometer, expressed in Relative Light Units (RLU). Effects of a simple sanitizing wipe-based disinfection routine were measured at baseline, and at 1, 3, 6, and 12 months after implementation of the disinfection routine.

RESULTS

Personal mobile phones and shared phones of 30 on-shift ICU nurses were analyzed at each collection. RLUs for personal phones decreased from baseline to 12 months post-intervention (Geometric mean 497.1 vs 63.36 RLU; adj P < .001), while shared unit phones also demonstrated a decrease from baseline to 12 months post-intervention (Geometric mean 417.4 vs 45.90 RLU; adj P < .001).

DISCUSSION

No recommended practice yet exists for disinfection of mobile phones in the acute care setting. The disinfection method and routine used in this study may have implications for use in acute care settings to reduce opportunities for infectious disease transmission.

Natural extracts, honey, and propolis as human norovirus inhibitors

Norovirus is the most important cause of acute gastroenteritis, yet there are still no antivirals, vaccines, or treatments available. Several studies have shown that norovirus-specific monoclonal antibodies, Nanobodies, and natural extracts might function as inhibitors. Therefore, the objective of this study was to determine the antiviral potential of additional natural extracts, honeys, and propolis samples. Norovirus GII.4 and GII.10 virus-like particles (VLPs) were treated with different natural samples and analyzed for their ability to block VLP binding to histo-blood group antigens (HBGAs), which are important norovirus co-factors. Of the 21 natural samples screened, date syrup and one propolis sample showed promising blocking potential. Dynamic light scattering indicated that VLPs treated with the date syrup and propolis caused particle aggregation, which was confirmed using electron microscopy. Several honey samples also showed weaker HBGA blocking potential. Taken together, our results found that natural samples might function as norovirus inhibitors.

Inactivation of Spores and Vegetative Forms of Clostridioides difficile by Chemical Biocides: Mechanisms of Biocidal Activity, Methods of Evaluation, and Environmental Aspects

Clostridioides difficile infections (CDIs) are the most common cause of acquired diseases in hospitalized patients. Effective surface disinfection, focused on the inactivation of the spores of this pathogen, is a decisive factor in reducing the number of nosocomial cases of CDI infections. An efficient disinfection procedure is the result of both the properties of the biocidal agent used and the technology of its implementation as well as a reliable, experimental methodology for assessing the activity of the biocidal active substance based on laboratory models that adequately represent real clinical conditions. This study reviews the state of knowledge regarding the properties and biochemical basis of the action mechanisms of sporicidal substances, with emphasis on chlorine dioxide (ClO₂). Among the analyzed biocides, in addition to ClO₂, active chlorine, hydrogen peroxide, peracetic acid, and glutaraldehyde were characterized. Due to the relatively high sporicidal effectiveness and effective control of bacterial biofilm, as well as safety in a health and environmental context, the use of ClO₂ is an attractive alternative in the control of nosocomial infections of CD etiology. In terms of the methods of assessing the biocidal effectiveness, suspension and carrier standards are discussed.

Risk of environmental transmission of norovirus infection from prior room occupants

BACKGROUND

Environmental contamination of norovirus (NoV) is believed to be a significant source for further transmission in hospitals.

AIM

To investigate the risk of acquiring NoV in a cleaned room previously occupied by a patient with NoV infection. The risk of having a roommate with recent NoV infection was also assessed.

METHODS

In a retrospective cohort, comprising 33,788 room stays at five infectious Disease wards in southern Sweden from 2013 to 2018, the risk of acquiring NoV infection after admission to an exposed or non-exposed room was analysed with uni- and multivariable statistical analysis, controlling for age, colonization pressure and any roommate. RNA sequencing of the NoV strains involved in suspected room transmission was also performed.

RESULTS

Five of the 1106 patients exposed to a room with a prior occupant with NoV infection and 49 in the non-exposed group acquired NoV infection. An association between NoV acquisition was found in the univariable analysis (odds ratio (OR) 3.3, P=0.01), but not when adjusting for potential confounders (OR 1.9, P=0.2). Sequencing of the NoV samples showed that only two of the five exposed patients with acquired NoV infection were infected by identical strains to the prior room occupant, inferring a room transmission risk of 0.2% (95% confidence interval 0.05-0.78%). None of the 52 patients who shared room with a roommate with NoV symptoms resolved for ≥48 h acquired NoV infection.

CONCLUSIONS

In absolute terms, the risk of room transmission of NoV is low. Discontinuation of isolation ≥48 h after resolution of symptoms seems adequate.

Current Understanding of Ultraviolet-C Decontamination of N95 Filtering Facepiece Respirators

Introduction: The COVID-19 pandemic has led to critical shortages of single-use N95 filtering facepiece respirators. The US Centers for Disease Control and Prevention has identified ultraviolet-C (UV-C) irradiation as one of the most promising decontamination methods during crisis-capacity surges; however, understanding the mechanism of pathogen inactivation and post-treatment respirator performance is central to effective UV-C decontamination. Objective: We summarize the UV-C N95 decontamination evidence and identify key metrics. Methods: We evaluate the peer-reviewed literature on UV-C decontamination to inactivate SARS-CoV-2, viral analogues, and other microorganisms inoculated on N95s, as well as the resulting effect on respirator fit and filtration. Where peer-reviewed studies are absent, we discuss outstanding questions and ongoing work. Key Findings: Evidence supports that UV-C exposure of ≥1.0 J/cm2 inactivates SARS-CoV-2 analogues (≥3-log reduction) on the majority of tested N95 models. The literature cautions that (1) viral inactivation is N95 model-dependent and impeded by shadowing, (2) N95 straps require secondary decontamination, (3) higher doses may be necessary to inactivate other pathogens (e.g., some bacterial spores), and (4) while N95 fit and filtration appear to be preserved for 10-20 cycles of 1.0 J/cm2, donning and doffing may degrade fit to unacceptable levels within fewer cycles. Results and Discussion: Effective N95 UV-C treatment for emergency reuse requires both (1) inactivation of the SARS-CoV-2 virus, achieved through application of UV-C irradiation at an appropriate wavelength and effective dose, and (2) maintenance of the fit and filtration efficiency of the N95. Conclusions: UV-C treatment is a risk-mitigation process that should be implemented only under crisis-capacity conditions and with proper engineering, industrial hygiene, and biosafety controls.

Efficacy of ultraviolet C exposure for inactivating Senecavirus A on experimentally contaminated surfaces commonly found on swine farms

The objective of this study was to evaluate the efficacy of ultraviolet C light (UVC) for inactivating Senecavirus A (SVA) on three different experimentally contaminated surfaces commonly found in swine farms. An experimental study under controlled conditions assessed the effect of UVC on an SVA isolate on coupons composed of three surface types: cardboard, cloth, and plastic. Each coupon was inoculated with 2 mL of SVA (10^7.5 TCID₅₀/mL) and 1 mL of PBS or 1 g of feces on the top or bottom surface of the coupon and allowed to dry (90 min at 25℃). Coupons were exposed to UVC in a commercially available pass-through chamber (PTC) for 5 min or in a simulated supply entry room (SER) for 120 min. After exposure, virus isolation was attempted from each coupon and virus titers were determined in cell culture. The efficacy of UVC was determined by the reduction in virus titer for the UVC treated groups compared to their respective non-treated positive controls. UVC was effective at inactivating SVA on plastic surface free of organic material. The plastic coupons inoculated with SVA and PBS had a significantly lower virus titer (>7-log reduction) in both the PTC and SER when compared to their relative positive controls. All other groups in the PTC and SER had a 2-log reduction or less. The reduction in virus titer on the top and bottom inoculated surfaces, following exposure to UVC, were not statistically different. The data from this study provide some guidance when applying UVC for disinfection in the field.

Disinfecting handheld electronic devices with UV-C in a healthcare setting

Handheld Electronic Devices (HEDs) play a central role in the hospital environment. However, they can be a vehicle for transmitting (pathogenic) microorganisms. We studied whether disinfection with UV-C light is successful in disinfecting three different HEDs in a clinical setting. Disinfection with UV-C light was performed with the UV-Smart® D25. We took a total of 800 samples on two departments and counted colony forming units. More than half of the baseline measurements were moderately (>10CFU) or highly (>50 CFU) contaminated. Post-disinfection the CFU was 0 in 87% of measurements. We conclude that the UV-Smart® D25 can be used to disinfect non-critical HEDs in clinical healthcare.

The impact of far-UVC radiation (200-230 nm) on pathogens, cells, skin, and eyes - a collection and analysis of a hundred years of data

Background: The ongoing coronavirus pandemic requires new disinfection approaches, especially for airborne viruses. The 254 nm emission of low-pressure vacuum lamps is known for its antimicrobial effect, but unfortunately, this radiation is also harmful to human cells. Some researchers published reports that short-wavelength ultraviolet light in the spectral region of 200-230 nm (far-UVC) should inactivate pathogens without harming human cells, which might be very helpful in many applications. Methods: A literature search on the impact of far-UVC radiation on pathogens, cells, skin and eyes was performed and median log-reduction doses for different pathogens and wavelengths were calculated. Observed damage to cells, skin and eyes was collected and presented in standardized form. Results: More than 100 papers on far-UVC disinfection, published within the last 100 years, were found. Far-UVC radiation, especially the 222 nm emission of KrCl excimer lamps, exhibits strong antimicrobial properties. The average necessary log-reduction doses are 1.3 times higher than with 254 nm irradiation. A dose of 100 mJ/cm2 reduces all pathogens by several orders of magnitude without harming human cells, if optical filters block emissions above 230 nm. Conclusion: The approach is very promising, especially for temporary applications, but the data is still sparse. Investigations with high far-UVC doses over a longer period of time have not yet been carried out, and there is no positive study on the impact of this radiation on human eyes. Additionally, far-UVC sources are unavailable in larger quantities. Therefore, this is not a short-term solution for the current pandemic, but may be suitable for future technological approaches for decontamination in rooms in the presence of people or for antisepsis.

Classical and alternative disinfection strategies to control the COVID-19 virus in healthcare facilities: a review

The coronavirus disease COVID-19 has spread throughout the world and has been declared as a pandemic by the World Health Organization on March 11th, 2020. The COVID-19 is caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). One possible mode of virus transmission is through surfaces in the healthcare settings. This paper reviews currently used disinfection strategies to control SARS-CoV-2 at the healthcare facilities. Chemical disinfectants include hypochlorite, peroxymonosulfate, alcohols, quaternary ammonium compounds, and hydrogen peroxide. Advanced strategies include no-touch techniques such as engineered antimicrobial surfaces and automated room disinfection systems using hydrogen peroxide vapor or ultraviolet light.

A review of wipes used to disinfect hard surfaces in health care facilities

BACKGROUND

Despite a plethora of wipes available for use in health care facilities, there is a paucity of articles describing wipe composition, potential interactions between wipes and disinfectants, the manner in which wipes are used, and their relative efficacy. The purpose of this article is to provide an in-depth review of wipes used for disinfection of hard surfaces in health care settings.

METHODS

Comprehensive searches of the Pubmed database and Internet were conducted, and articles published from 1953 through September 2019 and pertinent on-line documents were reviewed. Bibliographies of relevant articles were reviewed.

RESULTS

Wipes vary considerably in their composition, and the disinfectants with which they are used. With reusable dry wipes, the ratio of wipe material to disinfectant and the amount of disinfectant absorbed by the wipe and delivered to surfaces is difficult to standardize, which may affect their efficacy. The manner in which wipes are used by health care personnel is highly variable, due in part to insufficient instructions for use and inadequate education of relevant personnel.

CONCLUSIONS

Additional research is needed regarding the best practices for using different types of wipes, improved methods for educating staff, and establishing the relative efficacy of wipes in reducing environmental contamination and health care-associated infections.

Shining a light on the pathogenicity of health care providers' mobile phones: Use of a novel ultraviolet-C wave disinfection device

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Novel UV-C device found to significantly decrease total and pathogenic bacteria on mobile phones.

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UV-C phone disinfecting device is renewable, efficient and effective..

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UV-C device implementation in a hospital system would be desired by healthcare providers.

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Healthcare providers felt their mobile phones were an important risk factor in infection transmission and that they would use this device daily to weekly.

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UV-C technology is shown to kill coronaviruses and implementation of this device could be impactful during pandemic.

Background

Mobile phones are known to carry pathogenic bacteria and viruses on their surfaces, posing a risk to healthcare providers (HCPs) and hospital infection prevention efforts. We utilize an Ultraviolet-C (UV-C) device to provide an effective method for mobile phone disinfection and survey HCPs about infection risk.

Methods

Environmental swabs were used to culture HCPs’ personal mobile phone surfaces. Four cultures were obtained per phone: before and after the UV-C device's 30-second disinfecting cycle, at the beginning and end of a 12-hour shift. Surveys were administered to participants pre- and poststudy.

Results

Total bacterial colony forming units were reduced by 90.5% (P = .006) after one UV-C disinfection cycle, and by 99.9% (P = .004) after 2 cycles. Total pathogenic bacterial colony forming units were decreased by 98.2% (P = .038) after one and >99.99% (P = .037) after 2 disinfection cycles. All survey respondents were willing to use the UV-C device daily to weekly, finding it convenient and beneficial.

Discussion

This novel UV-C disinfecting device is effective in reducing pathogenic bacteria on mobile phones. HCPs would frequently use a phone disinfecting device to reduce infection risk.

Conclusions

In light of the ongoing coronavirus (COVID-19) pandemic, a standardized approach to phone disinfection may be valuable in preventing healthcare-associated infections.

Construction and validation of UV-C decontamination cabinets for filtering facepiece respirators

We present evidence-based design principles for three different UV-C based decontamination systems for N95 filtering facepiece respirators (FFRs) within the context of the SARS-CoV-2 outbreak of 2019-2020. The approaches used here were created with consideration for the needs of low- and middle-income countries (LMICs) and other under-resourced facilities. As such, a particular emphasis is placed on providing cost-effective solutions that can be implemented in short order using generally available components and subsystems. We discuss three optical designs for decontamination chambers, describe experiments verifying design parameters, validate the efficacy of the decontamination for two commonly used N95 FFRs (3M, #1860 and Gerson #1730), and run mechanical and filtration tests that support FFR reuse for at least five decontamination cycles.

Different efficacies of common disinfection methods against candida auris and other candida species

BACKGROUND

Candida auris can form long-lasting colonies in the hospital environment and on human skin. There is limited evidence regarding the efficacy of different methods and products for disinfecting hospitals and colonized patients to prevent the spread of C. auris.

METHODS

The minimum inhibitory concentration of three disinfectant products ("84" disinfectant, IodineTincture disinfectant, and quaternary ammonium) and 75% ethanol against C. auris and other Candida species were measured. A pig skin model was used to evaluate the efficacy of three hand hygiene products in killing pathogens. The killing effect of ultraviolet-C (253.7 nm) and the LK/CXD bed unit ozone disinfection machine on C. auris was also evaluated.

RESULTS

Thirty seconds of pig skin washing with bacteriostatic hand sanitizer followed by drying and 15 s of ethanol-based gel can completely eradicate the colonization of C. auris (3.00 log₁₀ CFU). The antifungal activity of ultraviolet-C to C. auris inoculated on bed sheets was significantly reduced (P < 0.01) at a distance of 1 m. Candida glabrata and C. auris showed greater resistance to ozone than other Candida species. The ozone could completely eradicate C. auris (3.60 log₁₀ CFU) on bed sheets at dosage of 300 mg/m³ for 40 min of exposure.

CONCLUSIONS

We recommend extending the disinfection times of ultraviolet-C and ozone and emphasizing the effectiveness of washing skin with soap, drying skin, and then applying an ethanol-based gel to remove C. auris from skin.