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.
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.
Background Surface sanitation is one of the key points to reduce the risk of transmission both in healthcare and other public spaces. UV-C is already used in hospital and laboratory's disinfection procedure furthermore some recent studies show effectiveness on SARS-CoV-2. UV-C may be generated by Lamps and Light Emitting Diode, but novel sources are emerging. The aim of the study was to test a device having UV chips for inactivating SARS-CoV2. Methods The descriptive study was conducted in the period between June and July 2019, in laboratories of the University of Siena and of the scientific park of Toscana life sciences. The device, shaped in a rectangular box, contained six UV chips (10 mW each, with a peak at 264nm nm ranging from 260 to 350 nm) placed in the bottom. Central and short side long positions were tested expecting different dose levels. Each experiment was conducted in triplicate, with and without the device lid, at 3, 6 and 10 minutes. All repetitions were tested for SARS-CoV-2 having a virus suspension of 10^7.2. Results The zones with the higher value of irradiance (max 187.9 µW/cm2) were near the corners of the box, while the lowest (min 61.9 µW/cm2) near one of the long sides. The light distribution was almost symmetrical. The tests revealed a viral charge reduction from an initial concentration of virus suspension of 10^7.2 TCID50/mL, of more than 99.9% after 3 minutes of UV exposure; at 6 minutes, the minimum Log10 attenuation value was over 5 Log10(99,999%); the maximum detectable attenuation value of Log10 = 5.7 was measured at 10 minutes. Conclusions This device is the first one which introduces this novel UV chip source, similarly it is the first time it was tested against the SARS-CoV-2. Objects that need to be disinfected may benefit of such devices according a proper exposition time for homogeneous disinfections of the surfaces. Key messages Implementation of cleaning and disinfection devices has been shown to reduce Sars-cov-2 infection incidence. In the hospital sanitation field, but also in public places and homes, using viable alternatives as UV-C can contribute to the reduction of pandemic spread.
Background Candida auris is an emerging pathogen responsible for several outbreaks within healthcare facilities. It can be found on hospital surfaces and patient care devices. UV- C sanitisation may constitute an effective adjunct to routine room cleaning to prevent the spreading of this yeast. Previous findings with this technology suggest to investigate different sources of variability in the study of the biocidal effect of UV devices on C. auris. In this study we develop a computer simulation of surface distribution of microorganisms on a stainless steel carrier, to optimize UV-device experiments. Methods Based on the literature about C. auris studies and its estimated average size (about 5 μm diameter), several Matlab simulations have been performed to include as many microorganisms as possible to be ideally placed on a 20 cm2 stainless steel support, avoiding cell overlapping. This was done in order to maximize the effectiveness of UV exposure. Results Two initial simulations were performed to evaluate a random arrangement of a very large number of microorganisms (8x107 CFU) on the steel support, widely overlapped. In this case, due to the poor UV-C penetrability, we would not exceed two log10 reduction. By randomly distributing 1x106 CFU, the probability of overlapping was about 1.3%, but even a partial overlap limits the log10 reduction. By randomly distributing 1x105 CFU, the overlaps were at least 10 times less likely. Conclusions The simulation results allowed us to evaluate the most appropriate microorganism distribution model able to optimize the biocidal effects of UV-C devices. The overlapping of microorganisms reduces UV-C penetrability. Our simulated study is consistent with literature results where we observed a lower log-reduction by increasing the concentration of microorganisms and therefore the probability of overlapping. The resulting model would simulate any log-reduction scenario, at any distance and any concentration, with and without overlapping. Key messages The complete or partial microorganism overlapping plays a relevant role in the outcome of UV-C biocidal experiments. To identify the exponential CFU reduction curve and estimate accurately the inactivation rate constant, simulated experiments should be performed to assess the real effectiveness of UV devices.
Background Facemasks (FM), due to the Covid-19 pandemic, are extensively used and often worn beyond the recommended time. This has led to questions about the negative impact persistent contamination on FMs might have on public health. The study aims to assess the level of contamination reached in a small cohort of subjects after the recommended use (8 h) of FM. Methods This descriptive study was carried out between January and April 2022 on 17 people: 9 women and 8 men aged between 25-45 years. These two groups were divided into two micro-groups: women were selected according to their skincare habits (no skincare and skincare with cosmetics). In contrast, men were selected according to the length of their beards (thick or short beard). The FM was worn for 8 h in a controlled office setting, to avoid possible uncontrolled variables. Then, the FM was cut, placed in a tube with a recovery medium and centrifuged. The supernatant was removed and the pellet resuspended. Aliquots were plated on Petri plates and incubated for 48 h at 36 °C to count the Colony Forming Units (CFU). The statistical analysis was conducted using Stata software, performing the Wilcoxon matched-pairs and setting a significance level of p < 0.05. Results Women had higher FM contamination than men (= 4960 vs 3130 CFU/ml). Also, we found more colonies (= 18890 vs 3420 CFU/ml) in the FMs of women without skincare (p = 0.06), while among men, more colonies were reported for those with a thicker beard than for those with a shorter one (= 3300 vs 2960 CFU/ml). Conclusions Extensive FM use increases bacterial contamination exponentially. This could lead to changes in the facial microbiome, inducing skin conditions (such as allergic dermatitis and acne). Facial skin conditions are important public health issues for people wearing FMs daily. In addition, responsible handling of this equipment is essential to avoid the spread of SARS-CoV-2 through contact with these items, which can persist for many days. Key messages • Gender and physical characteristics may influence the level of contamination present on FFP2 face masks. • There is a need to increase community awareness on the proper handling of facemasks, prevent health problems for users, and limit the spread of infection to those around them.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.