Staphylococcus aureus strains exhibit heterogenous tolerance to direct cold atmospheric plasma therapy

Abdullah Baz, Ahmed Bakri, Mark Butcher, Bryn Short, Bhagirath Ghimire, Nishtha Gaur, Toby Jenkins, Robert D. Short, Marcello Riggio, Craig Williams, Gordon Ramage, Jason L. Brown

Research output: Contribution to journalArticlepeer-review

4 Citations (SciVal)


The global clinical and socioeconomic impact of chronic wounds is substantial. The main difficulty that clinicians face during the treatment of chronic wounds is the risk of infection at the wound site. Infected wounds arise from an accumulation of microbial aggregates in the wound bed, leading to the formation of polymicrobial biofilms that can be largely resistant to antibiotic therapy. Therefore, it is essential for studies to identify novel therapeutics to alleviate biofilm infections. One innovative technique is the use of cold atmospheric plasma (CAP) which has been shown to possess promising antimicrobial and immunomodulatory properties. Here, different clinically relevant biofilm models will be treated with cold atmospheric plasma to assess its efficacy and killing effects. Biofilm viability was assessed using live dead qPCR, and morphological changes associated with CAP evaluated using scanning electron microscopy (SEM). Results indicated that CAP was effective against Candida albicans and Pseudomonas aeruginosa, both as mono-species biofilms and when grown in a triadic model system. CAP also significantly reduced viability in the nosocomial pathogen, Candida auris. Staphylococcus aureus Newman exhibited a level of tolerance to CAP therapy, both when grown alone or in the triadic model when grown alongside C. albicans and P. aeruginosa. However, this degree of tolerance exhibited by S. aureus was strain dependent. At a microscopic level, biofilm treatment led to subtle changes in morphology in the susceptible biofilms, with evidence of cellular deflation and shrinkage. Taken together, these results indicate a promising application of direct CAP therapy in combatting wound and skin-related biofilm infections, although biofilm composition may affect the treatment efficacy.

Original languageEnglish
Article number100123
Early online date15 Apr 2023
Publication statusPublished - 31 Dec 2023

Bibliographical note

Funding Information:
The authors acknowledge funding from Engineering and Physical Sciences Research Council (EPSRC) for supporting this project ( EP/V005839/1 ). In addition, authors would like to thank GlaxoSmithKline Consumer Healthcare and the BBSRC Industrial GlaxoSmithKline CASE PhD studentship for Mark C. Butcher ( BB/V509541/1 ), the King AbdulAziz University, Saudi Arabia , and Ministry of Health of Malaysia, Malaysia for funding Abdullah Baz and Ahmed Bakri, respectively. The authors would also like to extend their gratitude to the Glasgow Imaging Facility, and especially Margaret Mullin for her continued help and support with the processing and imaging of the biofilm samples for scanning electron microscopy. Finally, a thank you to Dr Joey Shepherd, University of Sheffield, for generously providing the S. aureus SH1000 strain.

Data availability
Data will be made available on request.


  • Biofilm
  • Candida albicans
  • Candida auris
  • Cold atmospheric plasma
  • Heterogeneity
  • Pseudomonas aeruginosa
  • Staphylococcus aureus
  • Tolerance

ASJC Scopus subject areas

  • Microbiology
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Cell Biology


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