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article imageEssential Science: Killing bacteria with new biocide mist

By Tim Sandle     Aug 13, 2018 in Science
The elimination of pathogenic bacteria is a key part of contamination control. However, many disinfectants are either not available in vapor form or they are harmful to users. A new ‘breathable mist’ offers a solution.
Researchers from University of California San Diego, have managed to turn a powerful and viscous disinfectant into breathable mist for the first time. This development could help with the much-needed fight against hospital-acquired infections.
Chemists and microbiologists have succeeded in producing a device that can diffuse potent disinfectants to enable airborne delivery. The new device operates with a range of disinfectants that have not been able to be atomized previously. The biocides tested include Triethylene glycol.
Triethylene glycol is well established as a relatively mild disinfectant toward a variety of bacteria, influenza A viruses and spores of Penicillium fungi. A key advantage is its low toxicity.
In trials, the researchers tested the device with disinfectant vapors against several environmental surfaces that had been artificially contaminated with bacteria. These tests showed that the device, using the appropriate disinfectant at the correct concentration and maintaining the appropriate contact time, could eliminate most of the bacteria on the surface. The types of bacteria tested were these associated with causing hospital-acquired infections.
Hospital infections
A hospital-acquired infection (nosocomial infection) refers to an infection acquired in a hospital or healthcare facility. The infection is spread to the susceptible patient in the clinical setting through different means. This includes transmission by healthcare personnel and infection via contaminated equipment, bed linens, or air droplets.
In addition, infections can originate from the outside environment or from another infected patient. In other cases the contaminating microorganism can originate from the patient's own microbiota as an opportunistic pathogen, becoming infectious due to the patient’s immune system being weak or compromised.
File photo: Nurses walk in a corridor on September 20  2013 at Lens  hospital
File photo: Nurses walk in a corridor on September 20, 2013 at Lens' hospital
Philippe Huguen, AFP/File
This means that regular disinfection is required.
The object of cleaning and disinfection is to achieve appropriate microbiological cleanliness levels for an appropriate period of time. A disinfectant is a type of chemical germicide which is capable of eliminating a population of vegetative microorganisms (in addition, some disinfectants are sporicidal).
A person practices the application of a disinfectant onto a cleaning cloth.
A person practices the application of a disinfectant onto a cleaning cloth.
New research
The scientists designed the new device using off-the-shelf smartphone components, which can trigger acoustic waves. The components generated sound waves at high frequencies (between 100 million to 10 billion hertz). These soundwaves served to produce fluid capillary waves, which emitted droplets and generated a mist (the process of atomization).
Conventional ways of turning a fluid to a most, such as using ultrasound, do not work well on viscous fluids. The new method overcomes this challenge. The smart phone components make use of Lithium Niobate. This is a material that produces more energy efficient and more reliable ultrasonic vibrations, allowing for the atomization of very viscous fluids, turning them into a fine mist that can drift in the air for over one hour.
According to lead researcher Dr. Monika Kumaraswamy: “Cleaning and disinfecting environmental surfaces in healthcare facilities is a critical infection prevention and control practice… This device will make it much easier to keep hospital rooms clean.”
Egyptian patient Eman Ahmed Abd El Aty lies in a hospital bed at The Saifee Hospital in Mumbai on Ma...
Egyptian patient Eman Ahmed Abd El Aty lies in a hospital bed at The Saifee Hospital in Mumbai on March 8, 2017, after her bariatric surgery
The effectiveness of the process will depend on the disinfectant selected, the area to be treated, the concentration of the disinfectant and the type of disinfectant selected. A further factor will be the type of bacteria and the population number, plus the presence of any interfering matter like blood protein residues.
Research paper
The research has been published in the journal Applied Microbiology and Biotechnology. The research paper is titled “Decontaminating surfaces with atomized disinfectants generated by a novel thickness-mode lithium niobate device.”
Essential Science
This article is part of Digital Journal's regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we learnt how the study of blue crystals in meteorites have shown that our Sun went through the astronomical equivalent of the 'terrible twos'.
The week before we considered research from University of Tasmania which outline the challenges facing scientists and policy makers as the result of increasing levels of carbon dioxide, which are being absorbed by the world's oceans.
More about disinfection, bioicide, Bacteria, Mist, Healthcare
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