Tag: sanitisation

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Wood May Have Natural Antiviral Properties

On By ModernMedia
Photo by National Cancer Institute on Unsplash

Thinking about getting a new desk for your practice? That might be a good idea. Viruses, including SARS-CoV-2, can get passed from person to person via contaminated surfaces. But can some surfaces reduce the risk of this type of transmission without the help of household disinfectants? As reported in ACS Applied Materials & Interfaces, wood has natural antiviral properties that can reduce the time viruses persist on its surface – and some species of wood are more effective than others at reducing infectivity.

Enveloped viruses, like the coronavirus, can live up to five days on surfaces; nonenveloped viruses, including enteroviruses linked to the common cold, can live for weeks, in some cases even if the surfaces are disinfected. Previous studies have shown that wood has antibacterial and antifungal properties, making it an ideal material for cutting boards. But wood’s ability to inactivate viruses has yet to be explored, which is what Varpu Marjomäki and colleagues set out to study.

The researchers looked at how long enveloped and nonenveloped viruses remained infectious on the surface of six types of wood: Scots pine, silver birch, gray alder, eucalyptus, pedunculate oak and Norway spruce. To determine viral activity, they flushed a wood sample’s surface with a liquid solution at different time points and then placed that solution in a petri dish that contained cultured cells. After incubating the cells with the solution, they measured the number (if any) infected with the virus.

Results from their demonstrations with an enveloped coronavirus showed that pine, spruce, birch and alder need one hour to completely reduce the virus’ ability to infect cells, with eucalyptus and oak needing two hours. Pine had the fastest onset of antiviral activity, beginning after five minutes. Spruce came in second, showing a sharp drop in infectivity after 10 minutes.

For a nonenveloped enterovirus, the researchers found that incubation on oak and spruce surfaces resulted in a loss of infectivity within about an hour, with oak having an onset time of 7.5 minutes and spruce after 60 minutes. Pine, birch and eucalyptus reduced the virus’ infectivity after four hours, and alder showed no antiviral effect.

Based on their study data, the researchers concluded that the chemical composition of a wood’s surface is primarily responsible for its antiviral functionality. While determining the exact chemical mechanisms responsible for viral inactivation will require further study, they say these findings point to wood as a promising potential candidate for sustainable, natural antiviral materials.

Source: American Chemical Society

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RSV Easier to Inactivate than Many Other Viruses

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Photo by Andrea Piacquadio on Unsplash

Every year, respiratory syncytial viruses (RSV) cause countless respiratory infections worldwide. For infants, young children and people with pre-existing conditions, the virus can be life-threatening and so clinicians are always on the look-out for ways to reduce infections. New research published in the Journal of Hospital Infection shows that, when used correctly, alcohol-based hand sanitisers and commercially available surface disinfectants provide good protection against transmission of the virus via surfaces.

Some viruses are known to remain infectious for a long time on surfaces. To determine this period for RSV, the Ruhr-University Bochum virology team examined how long the virus persists on stainless steel plates at room temperature. “Even though the amount of infectious virus decreased over time, we still detected infectious viral particles after seven days,” says Dr Toni Luise Meister. “In hospitals and medical practices in particular, it is therefore essential to disinfect surfaces on a regular basis.” Five surface disinfectants containing alcohol, aldehyde and hydrogen peroxide were tested and found to effectively inactivate the virus on surfaces.

RSV is easier to inactivate than some other viruses

Hand sanitisers recommended by the WHO also showed the desired effect. “An alcohol content of 30 percent was sufficient: we no longer detected any infectious virus after hand disinfection,” said Toni Luise Meister. RSV is thus easier to render harmless than some other viruses, such as mpox (formerly monkeypox) virus or hepatitis B virus.

Still, most infections with RSV are transmitted from one person to another, via airborne droplets. The risk of contracting the virus from an infected person decreases if that person rinses their mouth for 30 seconds with a commercial mouthwash. The lab tests showed that three mouthwashes for adults and three of four mouthwashes designed specifically for children reduced the amount of virus in the sample to below detectable levels.

“If we assume that these results from the lab can be transferred to everyday life, we are not at the mercy of seasonal flu and common cold, but can actively prevent infection,” concludes Toni Luise Meister. “In addition to disinfection, people should wash their hands regularly, maintain a proper sneezing and coughing etiquette, and keep their distance from others when they’re experiencing any symptoms.”

Source: Ruhr-University Bochum

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A New Easy-to-Apply Antimicrobial Coating

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Image by Quicknews

Researchers have developed an inexpensive, non-toxic coating for almost any fabric that decreases the infectivity of SARS-CoV-2 by up to 90%. It could even be developed to be applied to fabric by almost anyone.

“When you’re walking into a hospital, you want to know that pillow you’re putting your head onto is clean,” said lead author Taylor Wright, a doctoral student at the University of British Columbia. “This coating could take a little bit of the worry off frontline workers to have Personal Protection Equipment with antimicrobial properties.”

Researchers soaked fabric in a solution of an antimicrobial polymer which contains a molecule that releases reactive oxygen species when light shines on it. They then used UV light to turn this solution to a solid, fixing the coating to the fabric. “This coating has both passive and active antimicrobial properties, killing microbes immediately upon contact, which is then amped up when sunlight hits the cloth,” said senior author Professor Michael Wolf.

Both components are safe for human use, and the entire process takes about one hour at room temperature, said Wright. It also makes the fabric hydrophobic, without sacrificing fabric strength. The researchers detailed their study in American Chemical Society Applied Materials & Interfaces.

The coating can also be used on almost any fabric, with applications in hospital fabrics, masks, and activewear. While other such technologies can involve chemical waste, high energy use, or expensive equipment, the UBC method is relatively easy and inexpensive, said Wright. “All we need is a beaker and a light bulb. I’m fairly certain I could do the whole process on a stove.”

To test the coating’s antimicrobial properties, the researchers bathed treated fabric in bacterial soups of Escherichia coli and Methicillin-resistant Staphylococcus aureus (MRSA). They found that 85% of viable E. coli bacteria remained after 30 minutes, which fell to three per cent when the treated cloth was exposed to green light for the same amount of time. Similarly, 95% of viable MRSA bacteria remained, dropping to 35% under green light. No bacteria remained after four hours.

While sunlight or fluorescent lights have a lesser percentage of green in their spectrums, the team expects similar but less intense results for fabric exposed to those light sources, said Wright. “Particularly in the Pacific Northwest, it’s not always a sunny day. So, at all times you’re going to have that layer of passive protection and when you need that extra layer of protection, you can step into a lit room, or place the fabric in a room with a green light bulb – which can be found for about $35 online.”

The researchers also looked into whether the coating reduced the infectivity of SARS-CoV-2 by bathing treated fabric in a solution of the virus particles and then adding that solution to living cells to see if they could infect them. They found the passive properties were ineffective against the virus, but when treated fabric was exposed to green light for two hours, there was up to a 90% drop in the virus’ infectivity. “In other words, only one tenth of the amount of virus signal was detected on cells infected with the UV-fabric and light treated virus”, says co-author Professor François Jean.

The team found they needed an 18cm2 piece of fabric to kill microbes with material containing 7% of the active ingredient by weight, but that increasing this to 23% increased the effectiveness of the fabric at four times less material, said Wright.

Researchers also found that keeping the fabric under green light for more than 24 hours failed to produce the sterilising forms of oxygen, highlighting an area for further study. This is a similar effect to the colour fading on clothing after being exposed to sunlight for too long.

“Biomanufacturing face masks based on this new UBC technology would represent an important addition to our arsenal in the fight against COVID, in particular for highly transmissible SARS-CoV-2 variants of concern such as Omicron”, said Prof Jean. The coating can also be used for activewear, with an ‘anti-stink’ coating applied to areas where people tend to sweat, killing off the bacteria that makes us smell. Indeed, hospital fabric and activewear companies are already interested in applying the technology, and the university has applied for a patent in the United States, said Prof Wolf.

Source: University of British Columbia

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Microbes Develop Resistance to Disinfectant Too, Warns UFS Professor

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News-Medical.Net interviewed Professor Robert Bragg of the University of the Free State on the topic of pathogens, particularly bacteria, developing resistance to common disinfectants.

Professor Robert Bragg said that the control of diseases rests on three pillars: 1) vaccinations and vaccines, 2) treatment options (such as antibiotics for bacterial diseases), and 3) biosecurity.

Proff Brage explained that 10 to 15 years ago, there was an assumption that bacteria would not evolve resistance against disinfectants, but the COVID pandemic prompted a rethink. Now, disinfectant resistance is being looked at in the same light as antibiotic resistance. Biosecurity, he said, is ensuring that individuals do not come into contact with the pathogens in the first place. This is easily seen in the COVID pandemic, where face masks are worn (with a protection against contracting the disease of up to 70%), social distancing is enforced and hands and surfaces are sanitised. Though Prof Bragg’s main area of research is not antibiotic resistance, he notes that, “There are resistance mechanisms that are shared between antibiotics and disinfectants and we are looking at how these mechanisms increase resistance to disinfectants.” 

The protection of antibiotics is something taken for granted, but although mostly easily treatable (for now), bacteria can spread much faster than viruses, which require cells to reproduce in and whose re[plication rate is measured in days. “A common well-known bacterium such as Escherichia coli has a doubling time of around 20 min under ideal conditions. In other words, it only takes just 20 minutes for a population of E. coli to go from 1 million to 2 million and another 20 mins to reach 4 million, and so on,” Prof Bragg said. In the post-antibiotic era, there would be some treatment options such as bacteriophages, but for livestock the best protection would be biosecurity. However, disinfectant resistance would reduce the effectiveness of that option.

His research team has conducted a number of studies into the mechanisms of bacterial disinfectant resistance. “My research team has been working on various aspects of efficacy and resistance to disinfectants for quite some time and we have various projects that are currently underway,” he said. “Recently we identified a highly resistant strain of a Serratia species of bacteria. This strain was substantially more resistant to many different disinfectants than the reference strain. This great difference in the levels of susceptibility has allowed us to investigate various possible research mechanisms and also to look for possible novel resistance mechanisms.”

One of his team’s discoveries was that this highly resistant bacteria strain could grow on disinfectant if it was the sole source of carbon. Other areas of research around the resistant strain include sequencing and analysis of its genome, the role of bacterial efflux pumps removing disinfectant, and the role of plasmids (vehicles of genetic transfer between bacteria) in resistance and whether they are transferrable.

With regard to viruses, there are two kinds of viruses, enveloped and naked, and disinfectant has different effects on them. Enveloped viruses such as SARS-CoV-2, have a lipid layer picked up from their host cell, and are easy to kill with simple disinfectants because they break up the lipid layer, killing the cell. Naked cells are much harder to kill, and the few disinfectants that work against them are thought to do so by somehow disrupting the virus’ receptors.

One sanitiser of concern is alcohol, where 70% is considered optimal. However, people believe that ‘more is better’, yet increasing the alcohol percentage actually makes it evaporate faster, reducing contact time and thus leaving more of the virus behind. Similarly, some sanitisers include low levels of other disinfectant substances which are below the minimum threshold to kill the pathogens. This can leave surviving bacteria to develop resistance against these other sanitisers.

Prof Bragg advised that the public should purchase and use sanitisers prudently, following their instructions for use appropriately, and preferably checking to see if they are registered. He also cautioned

Source: News-Medical.Net