Inactivation of bacterial opportunistic skin pathogens by nonthermal DC-operated afterglow atmospheric plasma

Aims: Multidrug‐resistant opportunistic pathogens are clinically significant and require the development of new antimicrobial methods. In this study, Acinetobacter baumannii, Pseudomonas aeruginosa and Staphylococcus aureus cells were exposed to atmospheric plasma on agar plates and in vitro on porcine skin for the purpose of testing bacterial inactivation. Methods and Results: Microbial inactivation at varying exposure durations was tested using a nonthermal plasma jet generated with a DC voltage from ambient air. The observed reduction in colony forming units was quantified as log₁₀ reductions. Conclusions: Direct plasma exposure significantly inactivated seeded bacterial cells by approx. 6 log₁₀ on agar plates and 2–3 log₁₀ on porcine skin. On agar plates, an indirect ‘bystander’ inactivation outside the plasma delivery area was also observed. The reduced inactivation observed on the skin surface was most likely due to cell protection by the variable surface architecture. Significance and Impact of Study: Atmospheric plasma has potential for clinical application as a disinfectant of patient skin and medically relevant surfaces.