Violet-Blue Light Arrays at 405nm Exert Enhanced Antimicrobial Activity for Photodisinfection of Monomicrobial Nosocomial Related Biofilms.

Halstead, F D and Hadis, M A and Marley, N and Brock, K and Milward, M R and Cooper, P R and Oppenheim, B A and Palin, W M (2019) Violet-Blue Light Arrays at 405nm Exert Enhanced Antimicrobial Activity for Photodisinfection of Monomicrobial Nosocomial Related Biofilms. Applied and environmental microbiology. ISSN 1098-5336. This article is available to all UHB staff and students via ASK Discovery Tool http://tinyurl.com/z795c8c by using their UHB Athens login IDs.

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Official URL: https://aem.asm.org/content/early/2019/08/19/AEM.0...

Abstract

Light-emitting diodes (LEDs) demonstrate therapeutic effects for a range of biomedical applications including photodisinfection. Specific wavelength bands (centred at 405nm) are reported to be the most antimicrobial, however there remains no consensus on most effective irradiation parameters for optimal photodisinfection. The aim of this study was to assess decontamination efficiency by direct photodisinfection of monomicrobial biofilms using single (SWA), and multi wavelength (MWA) violet-blue light (VBL) arrays.Mature biofilms of nosocomial bacteria (, , and s) were grown on 96 well polypropylene PCR plates. The biofilms were then exposed to VBL for 2700 seconds (SWA) and 1170s (MWA), to deliver 0-670J/cm and the antibacterial activity of VBL assessed by comparing the seeding of the irradiated and non-irradiated biofilms. Non -irradiated groups were used as controls. VBL arrays were characterised optically (spectral irradiance and beam profile), and thermally.The SWA delivered 401nm VBL and the MWA delivered between 379 nm and 452nm albeit at different irradiances and beam profiles. In both arrays, irradiated groups were exposed to increased temperatures compared to non-irradiated controls. All bacterial isolates were susceptible to VBL and demonstrated reductions in seeding of exposed biofilms compared with non-irradiated controls. VBL at 405nm exerted the most antimicrobial activity, exhibiting reductions in seeding of up to 94%.Decontamination efficiency is dependent on irradiation parameters, bacterial species and strain, and experimental conditions. Controlled experiments that ameliorate heating effects and improve optical properties are required to optimise dosing parameters to advance successful clinical translation of this technology. This study reports the efficacy of VBL and BL, and its antimicrobial activity against mature biofilms of a range of important nosocomial pathogens. Whilst this study investigates the antibacterial activity of a range of wavelengths between 375-450nm, and identifies a specific wavelength region (∼405nm) with increased antibacterial activity, decontamination was dependent on bacterial species, strain, irradiation parameters and experimental conditions. Further research with controlled experiments that ameliorate heating effects, and improve optical properties are required to optimise dosing parameters to advance successful clinical translation of this technology.

Item Type: Article
Additional Information: This article is available to all UHB staff and students via ASK Discovery Tool http://tinyurl.com/z795c8c by using their UHB Athens login IDs.
Subjects: QW Microbiology. Immunology
Divisions: Clinical Support > Infection Control
Depositing User: Mrs Semanti Chakraborty
Date Deposited: 03 Sep 2019 16:00
Last Modified: 03 Sep 2019 16:00
URI: http://www.repository.uhblibrary.co.uk/id/eprint/2361

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