Comparison of hospital room surface disinfection using a novel ultraviolet germicidal irradiation (UVGI) generator

Superiority of manual disinfection using pre-soaked wipes over automatic UV-C radiation without prior cleaning

BACKGROUND

The efficacy of ultraviolet C (UV-C) radiation against a broad spectrum of micro-organisms has been demonstrated in several studies, but differences in the specific doses and the extent of microbial reduction were found. Furthermore, the conditions of laboratory tests differ greatly from reality, such that efficacy achieved in tests may not necessarily be assumed in reality. Consequently, it is important to investigate the effectiveness of UV-C in representative field trials. The aim was therefore to develop and establish a field test to evaluate automatic UV-C in comparison to manual disinfection.

METHODS

Before and after disinfection, samples were repeatedly collected from naturally highly contaminated surfaces using the swab technique to obtain representative data sets for disinfected and non-disinfected surfaces. Subsequently, the log reduction values (LRV) and the disinfection success were evaluated for UV-C radiation and full compliant manual disinfection using alcohol-based wipes.

RESULTS

Surfaces that are naturally contaminated with bacteria on a regular and nearly uniform basis have been identified as particularly suitable for field testing. Mean contamination was reduced from 23.3 to 1.98 cfu/cm2 (LRV 0.9) and 29.7 to 0.26 cfu/cm2 (LRV 1.2) for UV-C and manual disinfection, respectively. UV-C disinfection achieved 75.5% successful disinfected surfaces, whereas manual disinfection showed 98.1%.

CONCLUSIONS

Full compliant manual disinfection showed slightly higher LRVs and disinfection success than automatic UV-C disinfection. Successful, operator-independent UV-C disinfection still has the potential to improve disinfection performance in addition to manual disinfection.

Tolerance of clinical vancomycin-resistant Enterococcus faecium isolates against UV-C light from a mobile source

BACKGROUND

Admission to a room previously occupied by patients carrying environmentally robust pathogens implies an increased risk of acquiring those pathogens. Therefore, 'No-touch' automated room disinfection systems, including devices based on UV-C irradiation, are discussed to improve terminal cleaning. It is still unclear if clinical isolates of relevant pathogens behave differently under UV-C irradiation compared to laboratory strains used in the approval process of disinfection procedures. In this study we analysed the susceptibility of well characterized clonally divergent vancomycin-resistant enterococci (VRE) strains, including a linezolid-resistant isolate, against UV-C radiation.

METHODS

Susceptibility against UV-C of ten clonally divergent clinical isolates of VRE was determined in comparison to the commonly used test organism Enterococcus hirae ATCC 10541. Ceramic tiles contaminated with 105 to 106 colony forming units/25 cm² of the different enterococci were positioned at a distance of 1.0 and 1.5 m and irradiated for 20 s, resulting in a UV-C dose of 50 and 22 mJ/cm², respectively. Reduction factors were calculated after quantitative culture of the bacteria recovered from treated and untreated surfaces.

RESULTS

Susceptibility to UV-C varied considerably among the strains studied, with the mean value of the most robust strain being up to a power of ten lower compared to the most sensitive strain at both UV-C doses. The two most tolerant strains belonged to MLST sequence types ST80 and ST1283. The susceptibility of the laboratory strain E. hirae ATCC 10541 ranged between the most sensitive and most tolerant isolates for both irradiation doses. However, for UV-C dose of 22 mJ/cm², the reduction of the most tolerant isolate of ST1283 was statistically significantly lower compared to E. hirae ATCC 10541. The most susceptible strains belonged to the MLST sequence types ST117 and ST203.

CONCLUSIONS

These results indicate that UV-C doses reported in the literature are sufficient for the reduction of commonly used reference strains of enterococci but could be insufficient for the reduction of tolerant patient VRE-isolates in a hospital setting. Therefore, for future studies, the most tolerant clinical isolates should be used to validate automated UV-C devices or longer exposure times should be expected to ensure efficacy in the real world.

The effectiveness of phototherapy for surface decontamination against SARS-Cov-2. A systematic review

COVID-19 appeared in December 2019, needing efforts of science. Besides, a range of light therapies (photodynamic therapy, ultraviolet [UV], laser) has shown scientific alternatives to conventional decontamination therapies. Investigating the efficacy of light-based therapies for environment decontamination against SARS-CoV2, a PRISMA systematic review of Phototherapies against SARS-CoV or MERS-CoV species discussing changes in viral RT-PCR was done. After searching MEDLINE/PubMed, EMBASE, and Literatura Latino-Americana e do Caribe em Ciências da Saúde we have found studies about cell cultures irradiation (18), blood components irradiation (10), N95 masks decontamination (03), inanimate surface decontamination (03), aerosols decontamination (03), hospital rooms irradiation (01) with PDT, LED, and UV therapy. The best quality results showed an effective low time and dose UV irradiation for environments and inanimate surfaces without human persons as long as the devices have safety elements dependent on the surfaces, viral charge, humidity, radiant exposure. To interpersonal contamination in humans, PDT or LED therapy seems very promising and are encouraged.

Controlling microbial activity on walls by a photocatalytic nanocomposite paint: A field study

BACKGROUND

Bacteria and fungi that grow on the walls can cause allergic reactions and infectious diseases in human. We proposed a low-cost and easy-to-operate testing protocol for large scale field studies to evaluate the long-term antimicrobial performance of a novel WO_x paint in 2 primary schools.

METHODS

In Tun Mun and Tin Shui Wai schools, WO_x paints were painted on semi-outdoor and indoor walls and daily chlorine disinfection was applied after class in TSW School. A guidance was proposed for the protocol using the ATP biofluorescence method for large-scale field studies. ATP swab samples were taken at locations with and without the WO_x paint on a control basis with a sampling frequency once a week for three months. The ATP values were then processed and presented in box plots.

RESULTS

In both schools, the median log-scale ATP values of walls with WOx paint were at least 0.5-log lower than those without WOx paint. The WO_x paint also performed better than daily chlorine disinfection in reducing microbial activities in long-term.

CONCLUSIONS

The proposed testing protocol is suitable to evaluate long-term performance of an antimicrobial paint by analyzing its microbial activity in large-scale field tests. The WO_x paint shows long-term effectiveness in reducing microbial activities on wall surfaces in both indoor and semi-outdoor environments.

UV surface disinfection in a wearable drug delivery device

The advent of recombinant DNA technology fundamentally altered the drug discovery landscape, replacing traditional small-molecule drugs with protein and peptide-based biologics. Being susceptible to degradation via the oral route, biologics require comparatively invasive injections, most commonly by intravenous infusion (IV). Significant academic and industrial efforts are underway to replace IV transport with subcutaneous delivery by wearable infusion devices. To further complement the ease-of-use and safety of disposable infusion devices, surface disinfection of the drug container can be automated. For ease of use, the desired injector is a combination device, where the drug is inside the injector as a single solution combination device. The main obstacle of the desired solution is the inability to sterilize both injector and drug in the same chamber or using the same method (Gamma for the drug and ETO for the injector). This leads to the assembly of both drug container and injector after sterilization, resulting in at least one transition area that is not sterilized. To automate the delivery of the drug to the patient, a disinfection step before the drug delivery through the injector is required on the none-sterilized interface. As an innovative solution, the autoinjector presented here is designed with a single ultraviolet light-emitting diode (UV LED) for surface disinfection of the drug container and injector interface. In order to validate microbial disinfection similar to ethanol swabbing on the injector, a bacterial 3 or 6 log reduction needed to be demonstrated. However, the small disinfection chamber surfaces within the device are incapable of holding an initial bacterial load for demonstrating the 3 or 6 log reduction, complicating the validation method, and presenting a dilemma as to how to achieve the log reduction while producing real chamber conditions. The suggested solution in this paper is to establish a correlation model between the UV irradiance distribution within the disinfection chamber and a larger external test setup, which can hold the required bacterial load and represents a worse-case test scenario. Bacterial log reduction was subsequently performed on nine different microorganisms of low to high UV-tolerance. The procedure defined herein can be adopted for other surface or chamber disinfection studies in which the inoculation space is limited.

Nanoparticle Engineered Photocatalytic Paints: A Roadmap to Self-Sterilizing against the Spread of Communicable Diseases

Applications of visible-light photocatalytic engineered nanomaterials in the preparation of smart paints are of recent origin. The authors have revealed a great potential of these new paints for self-sterilizing of the surfaces in hospitals and public places simply with visible light exposure and this is reported for the first time in this review. A recent example of a communicable disease such as COVID-19 is considered. With all precautions and preventions taken as suggested by the World Health Organization (WHO), COVID-19 has remained present for a longer time compared to other diseases. It has affected millions of people worldwide and the significant challenge remains of preventing infections due to SARS-CoV-2. The present review is focused on revealing the cause of this widespread disease and suggests a roadmap to control the spread of disease. It is understood that the transmission of SARS-CoV-2 virus takes place through contact surfaces such as doorknobs, packaging and handrails, which may be responsible for many preventable and nosocomial infections. In addition, due to the potent transmissibility of SARS-CoV-2, its ability to survive for longer periods on common touch surfaces is also an important reason for the spread of COVID-19. The existing antimicrobial cleaning technologies used in hospitals are not suitable, viable or economical to keep public places free from such infections. Hence, in this review, an innovative approach of coating surfaces in public places with visible-light photocatalytic nanocomposite paints has been suggested as a roadmap to self-sterilizing against the spread of communicable diseases. The formulations of different nanoparticle engineered photocatalytic paints with their ability to destroy pathogens using visible light, alongwith the field trials are also summarized and reported in this review. The potential suggestions for controlling the spread of communicable diseases are also listed at the end of the review.

Back to Basics: Choosing the Appropriate Surface Disinfectant

From viruses to bacteria, our lives are filled with exposure to germs. In built environments, exposure to infectious microorganisms and their byproducts is clearly linked to human health. In the last year, public health emergency surrounding the COVID-19 pandemic stressed the importance of having good biosafety measures and practices. To prevent infection from spreading and to maintain the barrier, disinfection and hygiene habits are crucial, especially when the microorganism can persist and survive on surfaces. Contaminated surfaces are called fomites and on them, microorganisms can survive even for months. As a consequence, fomites serve as a second reservoir and transfer pathogens between hosts. The knowledge of microorganisms, type of surface, and antimicrobial agent is fundamental to develop the best approach to sanitize fomites and to obtain good disinfection levels. Hence, this review has the purpose to briefly describe the organisms, the kind of risk associated with them, and the main classes of antimicrobials for surfaces, to help choose the right approach to prevent exposure to pathogens.

Exploring the Composition and Functions of Plastic Microbiome Using Whole-Genome Sequencing

Besides the ecotoxicological consequences of microplastics and associated chemicals, the association of microbes on plastics has greater environmental implications as microplastics may select for unique microbiome participating in environmentally significant functions. Despite this, the functional potential of the microbiome associated with different types of plastics is understudied. Here, we investigate the interaction between plastic and marine biofilm-forming microorganisms through a whole-genome sequencing approach on four types of microplastics incubated in the marine environment. Taxonomic analysis suggested that the microplastic surfaces exhibit unique microbial profiles and niche partitioning among the substrates. In particular, the abundance of Vibrio alginolyticus and Vibrio campbellii suggested that microplastic pollution may pose a potential risk to the marine food chain and negatively impact aquaculture industries. Microbial genera involved in xenobiotic compound degradation, carbon cycling, and genes associated with the type IV secretion system, conjugal transfer protein TraG, plant-pathogen interaction, CusA/CzcA family heavy metal efflux transfer proteins, and TolC family proteins were significantly enriched on all the substrates, indicating the variety of processes operated by the plastic-microbiome. The present study gives a detailed characterization of the rapidly altering microbial composition and gene pools on plastics and adds new knowledge surrounding the environmental ramifications of marine plastic pollution.

Usos y limitaciones de la lámpara ultravioleta germicida portátil para la desinfección de superficies

RESUMENLa morbimortalidad causada por infecciones vinculadas a la atención sanatoria ha llevado a cuestionar si los métodos de desinfección convencionales son inadecuados y se requieren métodos complementarios, como la fumigación de la habitación y la irradiación ultravioleta. Ello ha dado lugar a la preocupación por que estos métodos alternativos puedan poner en riesgo al personal sanitario y a los pacientes.Objetivos. (1) Determinar la eficacia de la lámpara ultravioleta C germicida portátil para la desinfección de superficies, (2) evaluar el cambio de la humedad relativa (HR) y las distintas distancias específicas en las tasas de letalidad bacteriana, y (3) evaluar los posibles problemas a que conlleva la exposición.Métodos. En el presente estudio se investiga si una lámpara germicida portátil puede desinfectar de forma eficaz superficies tratadas con esporulación o germinación bacteriana y se evalúa el efecto de condiciones ambientales cambiantes, como la humedad relativa (HR), la posición y las distancias específicas, en las tasas de letalidad germicida.Resultados. Se constató una mejor tasa de letalidad con una HR de 40-65% y en un rango de temperatura de 21-24°C. Tanto la HR alta como la HR baja interfirieron con la capacidad de la radiación UV-C para inactivar la germinación microbiana. En el caso de la esporulación bacteriana, el aumento del secado de la superficie fue el factor de mayor importancia para aumentar la tasa de letalidad.Conclusiones. En esta investigación se demostró la eficacia de la radiación UV-C bajo condiciones óptimas, irradiación directa y una distancia específica corta (12.7 cm). Sin embargo, cuando es utilizada en condiciones que no son óptimas existen limitaciones. El aumento de la distancia y los ángulos de irradiación indirecta resultaron en tasas de letalidad más bajas. Cabe señalar que durante su uso es importante minimizar la exposición innecesaria de pacientes y personal sanitario.

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.

Ultraviolet-C decontamination of a hospital room: Amount of UV light needed

INTRODUCTION

Our primary aim was to investigate, using a commercial radiometer, the ultraviolet C (UVC) dose received in different areas in a burn ICU ward room after an automated UVC decontamination. The secondary aim was to validate a disposable UVC-dose indicator with the radiometer readings.

METHODS

Disposable indicators and an electronic radiometer were positioned in ten different positions in a burn ICU room. The room was decontaminated using the Tru-D™-UVC device. Colour changes of the disposable indicators and radiometer readings were noted and compared. Experiment was repeated 10 times.

FINDINGS

The UVC radiation received in different areas varied between 15.9mJ/cm² and 1068mJ/cm² (median 266mJ/cm²). Surfaces, at shorter distances and in the direct line of sight of the UVC device showed statistically significant higher UVC doses than surfaces in the shadow of equipment (p=0.019). The UVC-dose indicator's colour change corresponded with the commercially radiometer readings.

CONCLUSIONS

The amount of UVC radiation that is received in surfaces depends on their locations in the room (ie distance from the UVC emitter) and whether any objects shadow the light. In this study we suggest that quality controls should be used to assure that enough UVC radiation reaches all surfaces.

Assessment of focused multivector ultraviolet disinfection withshadowless delivery using 5-point multisided sampling ofpatientcare equipment without manual-chemical disinfection

BACKGROUND

The aim of this study was to evaluate the performance of a focused multivector ultraviolet (FMUV) system employing shadowless delivery with a 90-second disinfection cycle for patient care equipment inside and outside the operating room (OR) suite without manual-chemical disinfection.

METHODS

A 5-point multisided sampling protocol was utilized to measure the microbial burden on objects inside and outside the OR environment in a 3-phase nonrandomized observational study. Surface sampling was performed pre- and postdisinfection in between cases (IBCs) to assess the performance of manual-chemical disinfection. FMUV system performance was separately assessed pre- and postdisinfection before the first case and IBCs. Additionally, visibly clean high-touch objects were sampled outside the OR, and the microbial burden reductions after FMUV disinfection were quantified without manual-chemical disinfection.

RESULTS

Manual-chemical disinfection reduced the active microbial burden on sampled objects IBCs by 52.8%-90.9% (P < .05). FMUV reduced the active microbial burden by 92%-97.7% (P < .0001) before the firstcase and IBCs combined, and 96.3%-99.6% (P < .0001) on objects outside the OR without chemical disinfection.

CONCLUSIONS

Five-point multisided sampling proved effective for assessing disinfection performance on all exterior sides of equipment. FMUV produced significant overall reductions of the microbial burden on patient care equipment in all study phases and independent of manual cleaning and chemical disinfection.

Comparing and optimizing ultraviolet germicidal irradiation systems use for patient room terminal disinfection: an exploratory study using radiometry and commercial test cards

Background

Ultraviolet germicidal irradiation (UVGI) systems are gaining popularity, however objective comparisons of their characteristics are lacking. While environmental cultures and reduction of hospital-associated infections rates are excellent study endpoints, they are impractical for centers with limited resources who want to compare or optimize UVGI systems use.

Methods

We evaluated radiometry and commercial test cards, two simple and low cost tools, to compare 2 full size UVGI systems (Tru-D and Optimum-UV Enlight) and 2 small units (Lumalier EDU 435 and MRSA-UV Turbo-UV).

Results

Radiometry-derived output curves show that if both large devices emit enough energy to reach C. difficile lethal doses at 10 ft, the reduction in output in distance is almost perfectly logarithmic. In a patient room environment, Enlight and Tru-D performed similarly when compared using radiometry and commercial test cards. The two small devices reached C. difficile range around the bathroom with the device raised above the floor, but longer times are needed.

Conclusions

Despite different workflows and price points, no clear superiority emerges between Tru-D and Enlight. Bathroom disinfection should be dealt with separately from the main room and small, cheaper units can be used. Radiometry and commercial test cards are promising ways to compare UVGI systems, but further validation is needed using correlation with environmental cultures.

Trial registration

Not applicable.

Ambulance disinfection using Ultraviolet Germicidal Irradiation (UVGI): Effects of fixture location and surface reflectivity

Ambulances are frequently contaminated with infectious microorganisms shed by patients during transport that can be transferred to subsequent patients and emergency medical service workers. Manual decontamination is tedious and time-consuming, and persistent contamination is common even after cleaning. Ultraviolet germicidal irradiation (UVGI) has been proposed as a terminal disinfection method for ambulance patient compartments. However, no published studies have tested the use of UVGI in ambulances. The objectives of this study were to investigate the efficacy of a UVGI system in an ambulance patient compartment and to examine the impact of UVGI fixture position and the UV reflectivity of interior surfaces on the time required for disinfection. A UVGI fixture was placed in the front, middle, or back of an ambulance patient compartment, and the UV irradiance was measured at 49 locations. Aluminum sheets and UV-reflective paint were added to examine the effects of increasing surface reflectivity on disinfection time. Disinfection tests were conducted using Bacillus subtilis spores as a surrogate for pathogens. Our results showed that the UV irradiance varied considerably depending upon the surface location. For example, with the UVGI fixture in the back position and without the addition of UV-reflective surfaces, the most irradiated location received a dose of UVGI sufficient for disinfection in 16 s, but the least irradiated location required 15 hr. Because the overall time required to disinfect all of the interior surfaces is determined by the time required to disinfect the surfaces receiving the lowest irradiation levels, the patient compartment disinfection times for different UVGI configurations ranged from 16.5 hr to 59 min depending upon the UVGI fixture position and the interior surface reflectivity. These results indicate that UVGI systems can reduce microbial surface contamination in ambulance compartments, but the systems must be rigorously validated before deployment. Optimizing the UVGI fixture position and increasing the UV reflectivity of the interior surfaces can substantially improve the performance of a UVGI system and reduce the time required for disinfection.

Murthy AR. Laboratory Processing of Specimens

Although not always the first topic discussed when preparing for a bioemergency, the availability of a competent clinical laboratory is vital for the optimal care of a patient with a risk group 4 (RG-4) high-consequence pathogen. The recent development of highly specialized facilities in the United States to assess and treat patients with highly hazardous communicable diseases has led to the design of dedicated laboratories or the redesign of laboratory space to safely process and test specimens that might contain one of these pathogens. For frontline and other acute care facilities to be prepared, safety practices need to be assessed and reviewed as necessary as pertaining to all laboratory activities, to include the pre-analytical (specimen collection and processing), analytical (specimen testing), and post-analytical (specimen disposal/waste management and reporting) processes. Laboratorians and administrative personnel need to consider the risks in handling specimens containing these pathogens and subsequently develop or revise processes to mitigate risks. In addition, issues such as scalability to handle large volume testing, the availability of trained staff, and long-term sustainability to meet the requirements of regulatory agencies need to be adopted within a fiscally responsible budget setting. This chapter provides generalized information on how clinical laboratories, from those supporting small frontline medical facilities to highly specialized laboratories supporting acute care treatment centers, can safely manage specimens from a patient known or potentially infected with a high-consequence pathogen.

Effect of open ultraviolet germicidal irradiation lamps on functionality of excimer lasers used in cornea surgery

We report on the impact of direct ultraviolet germicidal irradiation (UVGI) on reflective optics, used in the excimer laser system Allegretto Eye-Q. The aim of our work was to confirm our hypothesis based on long-rate observations of obtained anomalies in post-operative results that are attributed to degradation of reflective optics upon ultraviolet radiation. The presence of direct UVGI coupled with humidity in the operating environment caused merging anomalies and unwanted post-operative correction values. Ultraviolet-A radiation caused a similar effect on the reflective cover of the mirrors.