Combating Porcine-Origin Multidrug-Resistant Staphylococcus aureus with a Traditional Chinese Medicine: In Vitro Efficacy and Mechanistic Insights

The emergence of multidrug-resistant bacteria poses a significant threat to global public health, highlighting the urgent need for novel, effective, and safe alternative agents to combat these pathogens. This study aimed to evaluate the in vitro antibacterial activity and mechanism of action of Galla chinensis extract (GCE) against porcine-origin Staphylococcus aureus . The bioactive components of Galla chinensis were extracted by water extraction with water-bath heating. The minimum inhibitory concentration (MIC) was determined using the two-fold broth microdilution method. The in vitro antibacterial activity of the GCE extract against S. aureus was evaluated by the disk diffusion assay and by monitoring bacterial growth curves at various extract concentrations. The antibacterial mechanism was investigated by assessing key indicators of bacterial membrane and envelope integrity following exposure to the extract. The GCE exhibited potent inhibitory activity against S. aureus , with an inhibition zone diameter of 3.60 ± 0.10 cm. The MIC of GCE against S. aureus was 15.63 mg/mL. Compared with the control group, bacterial growth was markedly suppressed in the extract-treated groups in a dose-dependent manner, with the inhibitory effect strengthening as the extract concentration increased. Following treatment, the alkaline phosphatase (AKP) activity, soluble protein concentration, and extracellular nucleic acid leakage of S. aureus increased in a concentration-dependent manner. Galla chinensis exhibits potent in vitro antibacterial activity against S. aureus by inhibiting bacterial growth, and its underlying mechanism is associated with disrupting the cell wall and cell membrane integrity of S. aureus .