Efficacy of Violet-Blue (405 nm) LED Lamps for Disinfection of High-Environmental-Contact Surfaces in Healthcare Facilities: Leading to the Inactivation of Microorganisms and Reduction of MRSA Contamination.

Effective disinfection procedures in healthcare facilities are essential to prevent transmission. Chemical disinfectants, hydrogen peroxide vapour (HPV) systems and ultraviolet (UV) light are commonly used methods. An emerging method, violet-blue light at 405 nm, has shown promise for surface disinfection. Its antimicrobial properties are based on producing reactive oxygen species (ROS) that lead to the inactivation of pathogens. Studies have shown significant efficacy in reducing bacterial levels on surfaces and in the air, reducing nosocomial infections. The aim of this study was to evaluate the antimicrobial effectiveness of violet-blue (405 nm) LED lamps on high-contact surfaces in a hospital infection-control laboratory. High-contact surfaces were sampled before and after 7 days of exposure to violet-blue light. In addition, the effect of violet-blue light on MRSA-contaminated surfaces was investigated. Exposure to violet-blue light significantly reduced the number of bacteria, yeasts and moulds on the sampled surfaces. The incubator handle showed a low microbial load and no growth after irradiation. The worktable and sink showed an inconsistent reduction due to shaded areas. In the second experiment, violet-blue light significantly reduced the microbial load of MRSA on surfaces, with a greater reduction on steel surfaces than on plastic surfaces. Violet-blue light at 405 nm has proven to be an effective tool for pathogen inactivation in healthcare settings Violet-blue light shows promise as an additional and integrated tool to reduce microbial contamination in hospital environments but must be used in combination with standard cleaning practices and infection control protocols. Further research is needed to optimise the violet-blue, 405 nm disinfection method.

Can a UV-C box help the cinema industry by disinfecting video cameras?

Introduction: UV-C has proven to be an effective virucide and microbicide, and its cost-effectiveness allowed it to spread as a disinfecting procedure in different environments. Methods: The study aims to determine the microbicide activity on Staphylococcus aureus, Escherichia coli and SARS-CoV-2 of the UV-C Boxer by Cartoni S.p.A. Three separate experiments were performed to assess the effectiveness of the UV-C disinfection device on different materials, directly on surfaces of a video camera and on a specific carrier for SARS-CoV-2. Results: In all three experiments, a significant abatement of bacterial and viral contamination was reached after 60 seconds on carriers and after 3 minutes on all examined surfaces of the video camera, with a higher reduction on glass carriers. Conclusions: UV-C devices may be a valuable tool to implement in the working routine to achieve a higher level of safety in work environments.

Effectiveness of near-UVA in SARS-CoV-2 inactivation.

This experimental study aimed to determine the activity of a near-UVA (405 nm) LED ceiling system against the SARS-CoV-2 virus. The ceiling system comprised 17 near-UVA LED lights with a radiant power of 1.1 W/each centred at 405 nm wavelength. A 96-multiwell plate, fixed to a wooden base, was inoculated with suspensions of VERO E6 cell cultures infected with SARS-CoV-2 virus and irradiated at a distance of 40 cm with a dose of 20.2 J/cm2 for 120 min. The collected suspensions were transferred to VERO cell culture plates and incubated for 3 days. The maximum measurable log reduction obtained, starting from a concentration of 107.2 TCID50/mL, was 3.0 log10 and indicated inhibition of SARS-CoV-2 replication by the near-UVA LED ceiling system. Near-UVA light at a 405-nm wavelength is emerging as a potential alternative treatment for localised infections and environmental decontamination because it is far less harmful to living organisms' cells than UV-C irradiation.

Efficacy of violet-blue light to inactive microbial growth.

The increase in health care-associated infections and antibiotic resistance has led to a growing interest in the search for innovative technologies to solve these problems. In recent years, the interest of the scientific community has focused on violet-blue light at 405 nm (VBL405). This study aimed to assess the VBL405 efficiency in reducing microbial growth on surfaces and air. This descriptive study run between July and October 2020. Petri dishes were contaminated with P. aeruginosa, E. coli, S. aureus, S. typhimurium, K. pneumoniae and were placed at 2 and 3 m from a LED light source having a wavelength peak at 405 nm and an irradiance respectively of 967 and 497 µW/cm2. Simultaneously, the air in the room was sampled for 5 days with two air samplers (SAS) before and after the exposition to the VBL405 source. The highest microbial reduction was reached 2 m directly under the light source: S. typhimurium (2.93 log10), K. pneumoniae (2.30 log10), S. aureus (3.98 log10), E. coli (3.83 log10), P. aeruginosa (3.86 log10). At a distance of 3 m from the light source, the greatest reduction was observed for S. aureus (3.49 log10), and P. aeruginosa (3.80 log10). An average percent microbial reduction of about 70% was found in the sampled air after 12 h of exposure to VBL405. VBL405 has proven to contrast microbial growth on the plates. Implementing this technology in the environment to provide continuous disinfection and to control microbial presence, even in the presence of people, may be an innovative solution.

An Emerging Innovative UV Disinfection Technology (Part II): Virucide Activity on SARS-CoV-2.

The coronavirus SARS-CoV-2 pandemic has become a global health burden. Surface sanitation is one of the key points to reduce the risk of transmission both in healthcare and other public spaces. UVC light is already used in hospital and laboratory infection control, and some recent studies have shown its effectiveness on SARS-CoV-2. An innovative UV chip technology, described in Part I of this study, has recently appeared able to overcome the limits of old lamps and is proposed as a valid alternative to LEDs. This study was designed to test the virucidal activity on SARS-CoV-2 of a device based on the new UV chip technology. Via an initial concentration of virus suspension of 107.2 TCID50/mL, the tests revealed a viral charge reduction of more than 99.9% after 3 min; the maximum detectable attenuation value of Log10 = 5.7 was measured at 10 min of UV exposure.

Geo-helminthiasis among migrants in Sicily: a possible focus for re-emerging neurocysticercosis in Europe.

A dramatic increasing immigration flow was recorded in Europe during the last years. Only in Sicily 120,239 people arrived in 2014. Immigrants may carry neglected tropical diseases endemic in their origin countries. The aim of our study was to evaluate the frequency of geo-helminthiasis, and in particular of intestinal taeniasis, in a sample of migrants hosted in a large asylum seeker centre in the province of Catania. A stool sample was obtained from all the enrolled subjects and a coproparasitological examination was performed. Out of the 274 enrolled subjects (249 men; mean age 26.4 ± 6.2), 30 (11%) carried at least one helminthic infestation. Ancylostomatidae, Trichuris trichiura and Taenia species (spp) were the most common, the latter found in 6 (2.16%) subjects. T. solium carriers can represent a focus of infection for the more complex neurocysticercosis. Even if coproparasitological examination did not allow us to differentiate Taenia spp, we cannot exclude the presence of T. solium carriers among these subjects. Further studies, including coproantigen ELISA to detect Taenia spp, should be carried out in larger samples to better estimate the real burden of T. solium carriers.