Susceptibility of Staphylococcus aureus biofilms to reactive discharge gases

Abstract

Formation of bacterial biofilms at solid–liquid interfaces creates numerous problems in both industrial and biomedical sciences. In this study, the susceptibility of Staphylococcus aureus biofilms to discharge gas generated from plasma was tested. It was found that despite distinct chemical/physical properties, discharge gases from oxygen, nitrogen, and argon demonstrated very potent and almost the same anti-biofilm activity. The bacterial cells in S. aureus biofilms were killed (>99.9%) by discharge gas within minutes of exposure. Under optimal experimental conditions, no bacteria and biofilm re-growth from discharge gas treated biofilms was found. Further studies revealed that the anti-biofilm activity of the discharge gas occurred by two distinct mechanisms: (1) killing bacteria in biofilms by causing severe cell membrane damage, and (2) damaging the extracellular polymeric matrix in the architecture of the biofilm to release biofilm from the surface of the solid substratum. Information gathered from this study provides an insight into the anti-biofilm mechanisms of plasma and confirms the applications of discharge gas in the treatment of biofilms and biofilm related bacterial infections.

Keywords:

• S. aureus
• bacterial biofilms
• plasma
• discharge gas
• susceptibility

Acknowledgements

The authors would like to thank Long Chen and Jinwoo Park for acquiring confocal microscopy and SEM images, respectively, and Dr Natalya Voloshchuk for conducting the chromosomal DNA analysis. This work was supported by NIH grant AI079608 and AI078716.