Impact of a dry inoculum deposition on the efficacy of copper-based antimicrobial surfaces

McDonald, M., Wesgate, R., Rubiano, M., Holah, J., Denyer, S. P., Jermann, C. and Maillard, J. -Y. ORCID: https://orcid.org/0000-0002-8617-9288 2020. Impact of a dry inoculum deposition on the efficacy of copper-based antimicrobial surfaces. Journal of Hospital Infection 106 (3) , pp. 465-472. 10.1016/j.jhin.2020.08.013

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Abstract

Background The introduction of antimicrobial surfaces into healthcare environments is believed to impact positively on the rate of healthcare-associated infections by significantly decreasing pathogen presence on surfaces. Aim To report on a novel efficacy test that uses a dry bacterial inoculum to measure the microbicidal efficacy of antimicrobial surfaces. Methods An aerosolized dry inoculum of Staphylococcus aureus or Acinetobacter baumannii was deposited on copper alloy surfaces or a hospital-grade stainless-steel surface. Surviving bacteria were enumerated following incubation of the inoculated surfaces at an environmentally relevant temperature and relative humidity. Damage caused to bacteria by the aerosolization process and by the different surfaces was investigated. Findings Dry inoculum testing showed a <2-log 10 reduction in S. aureus or A. baumannii on the copper alloy surfaces tested after 24 h at 20°C and 40% relative humidity. Potential mechanisms of action included membrane damage, DNA damage and arrested cellular respiration. The aerosolization process caused some damage to bacterial cells. Once this effect was taken into account, the antimicrobial activity of copper surfaces was evident. Conclusions Our test provided a realistic deposition of a bacterial inoculum to a surface and, as such, a realistic protocol to assess the efficacy of dry antimicrobial environmental surfaces in vitro.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Pharmacy
Publisher:	Elsevier
ISSN:	0195-6701
Date of First Compliant Deposit:	1 October 2020
Date of Acceptance:	11 August 2020
Last Modified:	21 Nov 2024 18:30
URI:	https://orca.cardiff.ac.uk/id/eprint/135242

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