Plasma activated water as a pre-treatment strategy in the context of biofilm-infected chronic wounds

Heema K N Vyas; Binbin Xia; David Alam; Nicholas P Gracie; Joanna G Rothwell; Scott A Rice; Dee Carter; Patrick J Cullen; Anne Mai-Prochnow

doi:10.1016/j.bioflm.2023.100154

Plasma activated water as a pre-treatment strategy in the context of biofilm-infected chronic wounds

Biofilm. 2023 Sep 19:6:100154. doi: 10.1016/j.bioflm.2023.100154. eCollection 2023 Dec 15.

Authors

Heema K N Vyas^{1

2}, Binbin Xia¹, David Alam¹, Nicholas P Gracie³, Joanna G Rothwell³, Scott A Rice^{4

5}, Dee Carter^{2

3}, Patrick J Cullen¹, Anne Mai-Prochnow¹

Affiliations

¹ School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, New South Wales, Australia.
² The Sydney Institute for Infectious Diseases, The University of Sydney, Sydney, New South Wales, Australia.
³ School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia.
⁴ Agriculture and Food, Microbiomes for One Systems Health, Commonwealth Scientific and Industrial Research Organisation, Sydney, New South Wales, Australia.
⁵ The Australian Institute for Microbiology and Infection, University of Technology Sydney, Sydney, New South Wales, Australia.

Abstract

Healing and treatment of chronic wounds are often complicated due to biofilm formation by pathogens. Here, the efficacy of plasma activated water (PAW) as a pre-treatment strategy has been investigated prior to the application of topical antiseptics polyhexamethylene biguanide, povidone iodine, and MediHoney, which are routinely used to treat chronic wounds. The efficacy of this treatment strategy was determined against biofilms of Escherichia coli formed on a plastic substratum and on a human keratinocyte monolayer substratum used as an in vitro biofilm-skin epithelial cell model. PAW pre-treatment greatly increased the killing efficacy of all the three antiseptics to eradicate the E. coli biofilms formed on the plastic and keratinocyte substrates. However, the efficacy of the combined PAW-antiseptic treatment and single treatments using PAW or antiseptic alone was lower for biofilms formed in the in vitro biofilm-skin epithelial cell model compared to the plastic substratum. Scavenging assays demonstrated that reactive species present within the PAW were largely responsible for its anti-biofilm activity. PAW treatment resulted in significant intracellular reactive oxygen and nitrogen species accumulation within the E. coli biofilms, while also rapidly acting on the microbial membrane leading to outer membrane permeabilisation and depolarisation. Together, these factors contribute to significant cell death, potentiating the antibacterial effect of the assessed antiseptics.

Keywords: Antiseptics; Biofilm; Chronic wounds; Escherichia coli; In vitro; Plasma activated water.