The discovery of the damaging effect of sunlight on bacteria

New Weapons to Fight against Staphylococcus aureus Skin Infections

The treatment of Staphylococcus aureus skin and soft tissue infections faces several challenges, such as the increased incidence of antibiotic-resistant strains and the fact that the antibiotics available to treat methicillin-resistant S. aureus present low bioavailability, are not easily metabolized, and cause severe secondary effects. Moreover, besides the susceptibility pattern of the S. aureus isolates detected in vitro, during patient treatment, the antibiotics may never encounter the bacteria because S. aureus hides within biofilms or inside eukaryotic cells. In addition, vascular compromise as well as other comorbidities of the patient may impede proper arrival to the skin when the antibiotic is given parenterally. In this manuscript, we revise some of the more promising strategies to improve antibiotic sensitivity, bioavailability, and delivery, including the combination of antibiotics with bactericidal nanomaterials, chemical inhibitors, antisense oligonucleotides, and lytic enzymes, among others. In addition, alternative non-antibiotic-based experimental therapies, including the delivery of antimicrobial peptides, bioactive glass nanoparticles or nanocrystalline cellulose, phototherapies, and hyperthermia, are also reviewed.

Does climate help modeling COVID-19 risk and to what extent?

A growing number of studies suggest that climate may impact the spread of COVID-19. This hypothesis is supported by data from similar viral contagions, such as SARS and the 1918 Flu Pandemic, and corroborated by US influenza data. However, the extent to which climate may affect COVID-19 transmission rates and help modeling COVID-19 risk is still not well understood. This study demonstrates that such an understanding is attainable through the development of regression models that verify how climate contributes to modeling COVID-19 transmission, and the use of feature importance techniques that assess the relative weight of meteorological variables compared to epidemiological, socioeconomic, environmental, and global health factors. The ensuing results show that meteorological factors play a key role in regression models of COVID-19 risk, with ultraviolet radiation (UV) as the main driver. These results are corroborated by statistical correlation analyses and a panel data fixed-effect model confirming that UV radiation coefficients are significantly negatively correlated with COVID-19 transmission rates.

A Review on Building Design as a Biomedical System for Preventing COVID-19 Pandemic

Sustainable design methods aim to obtain architectural solutions that assure the coexistence and welfare of human beings, inorganic structures, and living things that constitute ecosystems. The novel coronavirus emergence, inadequate vaccines against the present severe acute respiratory syndrome-coronavirus-(SARS-CoV-2), and increases in microbial resistance have made it essential to review the preventative approaches used during pre-antibiotic periods. Apart from low carbon emissions and energy, sustainable architecture for facilities, building designs, and digital modeling should incorporate design approaches to confront the impacts of communicable infections. This review aims to determine how architectural design can protect people and employees from harm; it models viewpoints to highlight the architects’ roles in combating coronavirus disease 2019 (COVID-19) and designing guidelines as a biomedical system for policymakers. The goals include exploring the hospital architecture evolution and the connection between architectural space and communicable infections and recommending design and digital modeling strategies to improve infection prevention and controls. Based on a wide-ranging literature review, it was found that design methods have often played important roles in the prevention and control of infectious diseases and could be a solution for combating the wide spread of the novel coronavirus or coronavirus variants or delta.

Does light-based tertiary treatment prevent the spread of antibiotic resistance genes? Performance, regrowth and future direction

The common occurrence of antibiotic-resistance genes (ARGs) originating from pathogenic and facultative pathogenic bacteria pose a high risk to aquatic environments. Low removal of ARGs in conventional wastewater treatment processes and horizontal dissemination of resistance genes between environmental bacteria and human pathogens have made antibiotic resistance evolution a complex global health issue. The phenomenon of regrowth of bacteria after disinfection raised some concerns regarding the long-lasting safety of treated waters. Despite the inactivation of living antibiotic-resistant bacteria (ARB), the possibility of transferring intact and liberated DNA containing ARGs remains. A step in this direction would be to apply new types of disinfection methods addressing this issue in detail, such as light-based advanced oxidation, that potentially enhance the effect of direct light interaction with DNA. This study is devoted to comprehensively and critically review the current state-of-art for light-driven disinfection. The main focus of the article is to provide an insight into the different photochemical disinfection methods currently being studied worldwide with respect to ARGs removal as an alternative to conventional methods. The systematic comparison of UV/chlorination, UV/H₂O₂, sulfate radical based-AOPs, photocatalytic processes and photoFenton considering their mode of action on molecular level, operational parameters of the processes, and overall efficiency of removal of ARGs is presented. An in-depth discussion of different light-dependent inactivation pathways, influence of DBP and DOM on ARG removal and the potential bacterial regrowth after treatment is presented. Based on presented revision the risk of ARG transfer from reactivated bacteria has been evaluated, leading to a future direction for research addressing the challenges of light-based disinfection technologies.

Identifying Health Care Environment Contradictions in Terms of Infection Control during a Pandemic with a Focus on Health Workers’ Experience

During the past year, health care environments have struggled to cope with the various impacts of COVID-19 around the world. Health care facilities need to help strengthen resistance to pathogen threats and provide care for patients and health workers in the safest possible way. Architectural design strategies can play a significant role in infection prevention and control. The current study aims to examine the experiences of health workers with hospital spaces during the COVID-19 pandemic. Identifying the difficulties they face, the present study attempts to shed light on the role of the health care layout configuration in combating pandemics. The authors conducted observations at four hospitals and a series of online semi-structured interviews with 162 health care staff from March to May 2020. The study indicated that space configuration and the hospitalization of patients, layout and circulation of the environment, operation services such as indoor environment conditions, maintenance of health care system, and organizational support for health care staff were the most critical factors affecting infection control in health care environments. The initial zoning and separation of patients were the most effective methods of controlling infection. Hospitals with clustered plan layouts were found to be the most effective buildings for the zoning of COVID-19 patients during the pandemic and for infection control.

Canopy distribution and microclimate preferences of sterile and wild Queensland fruit flies

Insects tend to live within well-defined habitats, and at smaller scales can have distinct microhabitat preferences. These preferences are important, but often overlooked, in applications of the sterile insect technique. Different microhabitat preferences of sterile and wild insects may reflect differences in environmental tolerance and may lead to spatial separation in the field, both of which may reduce the control program efficiency. In this study, we compared the diurnal microhabitat distributions of mass-reared (fertile and sterile) and wild Queensland fruit flies, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). Flies were individually tagged and released into field cages containing citrus trees. We recorded their locations in the canopies (height from ground, distance from canopy center), behavior (resting, grooming, walking, feeding), and the abiotic conditions on occupied leaves (temperature, humidity, light intensity) throughout the day. Flies from all groups moved lower in the canopy when temperature and light intensity were high, and humidity was low; lower canopy regions provided shelter from these conditions. Fertile and sterile mass-reared flies of both sexes were generally lower in the canopies than wild flies. Flies generally fed from the top sides of leaves that were lower in the canopy, suggesting food sources in these locations. Our observations suggest that mass-reared and wild B. tryoni occupy different locations in tree canopies, which could indicate different tolerances to environmental extremes and may result in spatial separation of sterile and wild flies when assessed at a landscape scale.

Lighting in the Home and Health: A Systematic Review

Poor housing is an important determinant of poor health. One key aspect of housing quality is lighting. Light is important for visual performance and safety, and also plays a vital role in regulating human physiological functions. This review aims to synthesise existing evidence on the relationship between lighting in the home and health and recommends areas for future research. Three databases were searched for relevant literature using pre-defined inclusion criteria. Study quality was assessed using the Newcastle Ottawa Scale. Extracted data were qualitatively synthesised according to type of lighting (natural light, artificial light and light at night) and stratified by broad health domains (physical, mental and sleep health). Of the 4043 records retrieved, 28 studies met the inclusion criteria. There was considerable heterogeneity in light exposure metrics used and specific health outcome assessed by the studies. Lighting in the home can negatively affect health but the current evidence base is limited to a small number of studies in different domains of light and health. Further research surrounding specific health outcomes is required to better inform housing quality assessments and lighting practises in the home.

Architectural design strategies for infection prevention and control (IPC) in health-care facilities: towards curbing the spread of Covid-19

Background

Sustainable design strategies are targeted at finding architectural solutions that reassure the well-being and coexistence of inorganic features, living organisms, and humans that make up the ecosystem. The emergence of the novel coronavirus, an increase in microbial resistance, and lack of a vaccine for the present pandemic have made it imperative to appraise the preventive strategies employed during the pre-antibiotic period. Sustainable architecture for children's hospital design and childcare facilities, apart from low energy and carbon emission, must integrate design strategies to confront the impact of infectious diseases.

Aim

The aim of the paper is to identify how the space patients and health-care workers0 occupy can be made safer from an architectural design perspective with the view of developing guidelines for policymakers and highlighting the architect's role in combating the pandemic.

Objectives

The objectives include; to examine the evolution of medical architecture and the nexus between infectious diseases and architectural space and suggest a design approach that enhances infection prevention and control (IPC).

Method

The paper relied on existing literature, interviews, and interactions with healthcare workers.

Results/Conclusion

The findings showed that design strategies have always played a significant role in infection prevention and control (IPC) and could as well be a panacea for curbing the spread of Covid -19.

Distribution of the SARS-CoV-2 Pandemic and Its Monthly Forecast Based on Seasonal Climate Patterns

This paper investigates whether the Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) pandemic could have been favored by specific weather conditions and other factors. It is found that the 2020 winter weather in the region of Wuhan (Hubei, Central China)—where the virus first broke out in December and spread widely from January to February 2020—was strikingly similar to that of the Northern Italian provinces of Milan, Brescia and Bergamo, where the pandemic broke out from February to March. The statistical analysis was extended to cover the United States of America, which overtook Italy and China as the country with the highest number of confirmed COronaVIrus Disease 19 (COVID-19) cases, and then to the entire world. The found correlation patterns suggest that the COVID-19 lethality significantly worsens (4 times on average) under weather temperatures between 4 °C and 12 °C and relative humidity between 60% and 80%. Possible co-factors such as median population age and air pollution were also investigated suggesting an important influence of the former but not of the latter, at least, on a synoptic scale. Based on these results, specific isotherm world maps were generated to locate, month by month, the world regions that share similar temperature ranges. From February to March, the 4–12 °C isotherm zone extended mostly from Central China toward Iran, Turkey, West-Mediterranean Europe (Italy, Spain and France) up to the United State of America, optimally coinciding with the geographic regions most affected by the pandemic from February to March. It is predicted that in the spring, as the weather gets warm, the pandemic will likely worsen in northern regions (United Kingdom, Germany, East Europe, Russia and North America) while the situation will likely improve in the southern regions (Italy and Spain). However, in autumn, the pandemic could come back and affect the same regions again. The Tropical Zone and the entire Southern Hemisphere, but in restricted colder southern regions, could avoid a strong pandemic because of the sufficiently warm weather during the entire year and because of the lower median age of their population. Google-Earth-Pro interactive-maps covering the entire world are provided as supplementary files.

Light as a potential treatment for pandemic coronavirus infections: A perspective

The recent outbreak of COVID-19, which continues to ravage communities with high death tolls and untold psychosocial and catastrophic economic consequences, is a vivid reminder of nature's capacity to defy contemporary healthcare. The pandemic calls for rapid mobilization of every potential clinical tool, including phototherapy—one of the most effective treatments used to reduce the impact of the 1918 “Spanish influenza” pandemic. This paper cites several studies showing that phototherapy has immense potential to reduce the impact of coronavirus diseases, and offers suggested ways that the healthcare industry can integrate modern light technologies in the fight against COVID-19 and other infections. The evidence shows that violet/blue (400–470 nm) light is antimicrobial against numerous bacteria, and that it accounts for Niels Ryberg Finsen's Nobel-winning treatment of tuberculosis. Further evidence shows that blue light inactivates several viruses, including the common flu coronavirus, and that in experimental animals, red and near infrared light reduce respiratory disorders, similar to those complications associated with coronavirus infection. Moreover, in patients, red light has been shown to alleviate chronic obstructive lung disease and bronchial asthma. These findings call for urgent efforts to further explore the clinical value of light, and not wait for another pandemic to serve as a reminder. The ubiquity of inexpensive light emitting lasers and light emitting diodes (LEDs), makes it relatively easy to develop safe low-cost light-based devices with the potential to reduce infections, sanitize equipment, hospital facilities, emergency care vehicles, homes, and the general environment as pilot studies have shown.

Durability of Selected Transparent and Semi-Transparent Coatings on Siberian and European Larch during Artificial Weathering

This paper compares the resistance of 20 commercial transparent and semi-transparent coatings applied to European and Siberian larch during artificial weathering in Xenotest. The change in gloss, colour, contact angle of wetting, resistance to Aspergillus niger and Penicillium brevicompactum moulds was evaluated, and visual changes at the top surface of treated wood species were measured. Overall, the durability of coatings on European larch was higher than that on Siberian larch. The most durable of the tested coatings was a thin-film, i.e., semi-transparent oil-based film containing TiO2 pigment and propiconazole fungicide. Of the transparent coatings, the most stable was a thick acrylic coating. Conversely, penetrating transparent oil systems had low colour stability and overall lifespan. Artificial weathering of all of the coatings resulted in a marked decrease in their resistance to moulds.

Daylight exposure modulates bacterial communities associated with household dust

BACKGROUND

Microbial communities associated with indoor dust abound in the built environment. The transmission of sunlight through windows is a key building design consideration, but the effects of light exposure on dust communities remain unclear. We report results of an experiment and computational models designed to assess the effects of light exposure and wavelengths on the structure of the dust microbiome. Specifically, we placed household dust in replicate model "rooms" with windows that transmitted visible, ultraviolet, or no light and measured taxonomic compositions, absolute abundances, and viabilities of the resulting bacterial communities.

RESULTS

Light exposure per se led to lower abundances of viable bacteria and communities that were compositionally distinct from dark rooms, suggesting preferential inactivation of some microbes over others under daylighting conditions. Differences between communities experiencing visible and ultraviolet light wavelengths were relatively minor, manifesting primarily in abundances of dead human-derived taxa. Daylighting was associated with the loss of a few numerically dominant groups of related microorganisms and apparent increases in the abundances of some rare groups, suggesting that a small number of microorganisms may have exhibited modest population growth under lighting conditions. Although biological processes like population growth on dust could have generated these patterns, we also present an alternate statistical explanation using sampling models from ecology; simulations indicate that artefactual, apparent increases in the abundances of very rare taxa may be a null expectation following the selective inactivation of dominant microorganisms in a community.

CONCLUSIONS

Our experimental and simulation-based results indicate that dust contains living bacterial taxa that can be inactivated following changes in local abiotic conditions and suggest that the bactericidal potential of ordinary window-filtered sunlight may be similar to ultraviolet wavelengths across dosages that are relevant to real buildings.

One-step deposition of a melanin-like polymer on individual Escherichia coli cells exhibiting a special UV resistance effect

Melanin-like polydopamine encapsulated E. coli cells could retained cells viability, inhibited cell division and protected cells from UV radiation. These provide both fundamental research and applications of cell encapsulation for UV resistance.

Roles of sunlight and natural ventilation for controlling infection: historical and current perspectives

Background

Infections caught in buildings are a major global cause of sickness and mortality. Understanding how infections spread is pivotal to public health yet current knowledge of indoor transmission remains poor.

Aim

To review the roles of natural ventilation and sunlight for controlling infection within healthcare environments.

Methods

Comprehensive literature search was performed, using electronic and library databases to retrieve English language papers combining infection; risk; pathogen; and mention of ventilation; fresh air; and sunlight. Foreign language articles with English translation were included, with no limit imposed on publication date.

Findings

In the past, hospitals were designed with south-facing glazing, cross-ventilation and high ceilings because fresh air and sunlight were thought to reduce infection risk. Historical and recent studies suggest that natural ventilation offers protection from transmission of airborne pathogens. Particle size, dispersal characteristics and transmission risk require more work to justify infection control practices concerning airborne pathogens. Sunlight boosts resistance to infection, with older studies suggesting potential roles for surface decontamination.

Conclusions

Current knowledge of indoor transmission of pathogens is inadequate, partly due to lack of agreed definitions for particle types and mechanisms of spread. There is recent evidence to support historical data on the effects of natural ventilation but virtually none for sunlight. Modern practice of designing healthcare buildings for comfort favours pathogen persistence. As the number of effective antimicrobial agents declines, further work is required to clarify absolute risks from airborne pathogens along with any potential benefits from additional fresh air and sunlight.

Bacterial sunscreen: layer-by-layer deposition of UV-absorbing polymers on whole-cell biosensors

UV-protective coatings on live bacterial cells were created from the assembly of cationic and UV-absorbing anionic polyelectrolytes using layer-by-layer (LbL) methodology. A cationic polymer (polyallylamine) and three different anionic polymers with varying absorbance in the UV range (poly(vinyl sulfate), poly(4-styrenesulfonic acid), and humic acid) were used to encapsulate Escherichia coli cells with two different green fluorescent protein (GFP) expression systems: constitutive expression of a UV-excitable GFP (GFPuv) and regulated expression of the intensely fluorescent GFP from amphioxus (GFPa1) through a theophylline-inducible riboswitch. Riboswitches activate protein expression after specific ligand-RNA binding events. Hence, they operate as a cellular biosensor that will activate reporter protein synthesis after exposure to a ligand target. E. coli cells coated with UV-absorbing polymers demonstrated enhanced protection of GFP stability, metabolic activity, and viability after prolonged exposure to radiation from a germicidal lamp. The results show the effectiveness of LbL coatings to provide UV protection to living cells for biotechnological applications.

The history of ultraviolet germicidal irradiation for air disinfection

Public health concerns such as multi- and extensive drug-resistant tuberculosis, bioterrorism, pandemic influenza, and severe acute respiratory syndrome have intensified efforts to prevent transmission of infections that are completely or partially airborne using environmental controls. One such control, ultraviolet germicidal irradiation (UVGI), has received renewed interest after decades of underutilization and neglect. With renewed interest, however, come renewed questions, especially regarding efficacy and safety. There is a long history of investigations concluding that, if used properly, UVGI can be safe and highly effective in disinfecting the air, thereby preventing transmission of a variety of airborne infections. Despite this long history, many infection control professionals are not familiar with the history of UVGI and how it has, and has not, been used safely and effectively. This article reviews that history of UVGI for air disinfection, starting with its biological basis, moving to its application in the real world, and ending with its current status.