INFECTION PREVENTION UV disinfection
UV light is commonly used in hospitals, but again efficacy is low, as discussed in an EPA report from Duke University in the US,5
where log reductions of only 2 to 4 were observed for species such as murine norovirus, even in highly controlled surface water treatments. UV radiation also has drawbacks, both in shadowing and reach, dramatically weakening with distance due to the effects of the inverse square law for electromagnetic radiation. Lamps supplied for UV disinfection should carry certificates of validation, but users must be cautious. Validation of a UV light source will be under strict laboratory conditions, and against specific species in controlled environments. In the real world, efficacy against various pathogens varies, and can be minimal, even under properly observed operating procedures, and, as with manual cleaning techniques, it is impossible to validate the disinfection process without scrupulously swabbing all surfaces to look for resistant contamination.
Hydrogen peroxide O2
In recent years, hydrogen peroxide (H2
References 1 Medam S, Zieleskiewicz L, Duclos G et al. Risk factors for death in septic shock: A retrospective cohort study comparing trauma and non-trauma patients. Medicine (Baltimore) 2017; 96 (50): e9241.
2 McCullough AR, Pollack AJ, Plejdrup Hansen M et al. Antibiotics for acute respiratory infections in general practice: comparison of prescribing rates with guideline recommendations. Med J Aust 2017; 207 (2): 65-9.
3 Perry C, Hall C. Antibiotic resistance: How it arises, the current position and future strategies. Nurs Times 2009; 105 (36): 20-3.
All BioGen’s new family of VHP-U generators – marketed by Howorth Air Technology – are designed around ‘next generation’ vapourised hydrogen peroxide (H2
O2
) has become popular as a biocide, showing potentially high efficacy, and decomposing safely to water and oxygen. However, cheap technologies such as direct application and so called ‘fogging’ using low concentration (typically 5-7%) H2
O2 ) technology.
have been shown to be ineffective without inclusion of additives such as silver, in the form of silver nitrate, leaving toxic residues; and oxidising agents such as peracetic acid, with toxicity and odour issues. Fogging uses an atomisation process, creating large droplet sizes prone to directional constraints, so it can be difficult, using the process, to reach shadowed areas and small spaces. Under ideal conditions, and using enhancing agents, foggers will give 6 log reduction, but this technology, along with manual techniques and UV light, have a level of ‘hit and miss’ that will leave users at risk of under-performance. Interestingly, foggers, when used, are often not validated, but merely evaluated using settle plates, which give no indication of surface disinfection.
An effective biocide There is no doubt that H2
O2 is an effective
biocide, and the use of a much higher concentration vapourised hydrogen peroxide dispersal method shows very high efficacy, giving >6 log reduction. Requiring no additives, the process is also residue and odour-free. VHP-U technology is also fully validatable, using enzyme or biological indicators, removing the uncertainty of efficacy given by manual disinfection techniques, UV, and H2
O2 fogging. Technology such as a VHP-U generator 70 Health Estate Journal October 2018
will create a disinfected, aseptic environment, killing airborne, as well as surface bioburden. However, this area will gradually pick up contamination from airborne particulates and human activity. Proper hygiene control and biocide retreatment on a regular basis will avoid bacterial, fungal, or viral build-up to levels that will cause potential for sepsis. Periods between disinfection treatments can be increased still further with technology that has recently developed – air purification combining HEPA filtration and airborne pathogen removal. This technology can be fully automated, and can operate under positive or negative pressure if necessary.
Conclusion
Treatment of ICUs, operating theatres, and recovery rooms, using technologies such as VHP-U disinfection and biocide air purification, gives assurance that the risk of sepsis is minimised, with the added confidence of full validation for VHP-U effectiveness. Lifetime cost of ownership is optimised, as periods between disinfection cycles are lengthened, with the financial benefit of less biocide use over time. An automated, validated
decontamination regime, such as the BioGen VHP-U generator with Genano air purification system, gives highly effective infection control and excellent return on investment. Many less operator hours are required when undertaking cleaning regimes using these technologies, with consistency of performance assured. Put simply, a VHP-U generator, combined with airborne pathogen management, creates a safer patient environment.
4 Quinn MM, Henneberger PK; National Institute for Occupational Safety and Health (NIOSH), National Occupational Research Agenda (NORA) Cleaning and Disinfecting in Healthcare Working Group et al. Cleaning and disinfecting environmental surfaces in healthcare: Toward an integrated framework for infection and occupational illness prevention. Am J Infect Control 2015; 43 (5): 424-34.
5 Linden KG, Sobsey MD. Effectiveness of UV irradiation for pathogen inactivation in surface waters. Duke University, University of North Carolina. August 2005.
Chris Smith
Chris Smith, Business Development manager at Howorth Air Technology, has 30 years’ life science experience in a variety of supply companies, including Beckman-Coulter, Varian, Shimadzu, and GE Healthcare. Howorth is best known for innovations in the healthcare arena, but is also, it says, ‘a world-class supplier of restricted access barrier systems (RABS) and isolators to the pharmaceutical industry’, and boasts a comprehensive range of aseptic solutions.
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