The concentrations of hydrogen peroxide (A), ozone (B), and nitrate (C) produced by NTP treatment with 8.1, 16.2, and 24.3 kJ applied energies, respectively. (D) The intracellular ROS level and (E) ATP level in Staphylococcus aureus cells under NTP treatment with 8.1, 16.2, and 24.3 kJ applied energies. Different lowercase letters mean a significant difference at P < 0.05.