Small-Molecule Inhibitors Targeting Bacterial Antioxidants Potentiate Bactericidal Efficacy of Cold Atmospheric...

Antibiotic-resistant Staphylococcus aureus infections pose a formidable clinical challenge. Cold atmospheric plasma (CAP) has emerged as a promising disinfection technology; however, the underlying bacterial response mechanisms and potential resistance to CAP remain incompletely elucidated. Here, we validated the broad-spectrum and efficient bactericidal activity of CAP against both drug-sensitive and drug-resistant clinical isolates of S. aureus. Mechanistically, CAP primarily eliminated bacteria by inducing oxidative damage to proteins and lipids, thereby disrupting internal cellular structures. The addition of exogenous free radical scavengers significantly attenuated CAP-mediated oxidative killing. Transcriptomic analysis and RT-qPCR validation further revealed upregulation of redox-related genes in S. aureus following CAP exposure. Deletion of key antioxidant genes, particularly ahpC and mrgA, markedly enhanced bacterial susceptibility to CAP. Virtual screening and surface plasmon resonance analysis identified two small-molecular inhibitors, C4515 and A8226, which specifically target AhpC and MrgA, respectively, and potentiated CAP bactericidal efficacy. Collectively, this study delineates the molecular interactions between CAP and S. aureus, and underscores the potential of CAP-based strategies for combating drug-resistant bacterial infections.