Dual-mechanism adjuvant catharanthine restores β-lactam efficacy against Staphylococcus aureus infections.

Staphylococcus aureus (S. aureus) remains a major global health threat with high mortality, causing both community-associated and hospital-acquired infections. Consequently, resistance mechanisms, notably β-lactamase production and biofilm formation, are considered promising therapeutic targets. In this study, Catharanthine, a plant-derived alkaloid extracted from Catharanthus roseus (Madagascar periwinkle), is a potent adjuvant that restores the efficacy of β-lactam antibiotics against S. aureus. This study aimed to investigate resistance mechanisms, notably β-lactamase production and biofilm formation, which are considered promising therapeutic targets. Molecular docking was performed to evaluate the binding interaction between catharanthine and β-lactamase. Metabolomic analysis was used to investigate the effect of catharanthine on bacterial metabolic pathways, particularly those associated with biofilm formation. In addition, murine models of S. aureus pneumonia and skin infection were established to assess the therapeutic efficacy of combination treatment with catharanthine and cefixime in vivo. Catharanthine showed high-affinity binding to β-lactamase in molecular docking analysis, supporting its potential role as a β-lactam antibiotic adjuvant. Metabolomic profiling revealed that catharanthine perturbed glutamate-associated amino acid metabolism involving the arginine biosynthetic network, thereby impairing biofilm development. In vivo, combination therapy with catharanthine and cefixime effectively alleviated infection in murine models of S. aureus pneumonia and skin infection. This study demonstrates that catharanthine enhances the therapeutic efficacy of β-lactam antibiotics through dual targeting of β-lactamase-associated resistance and biofilm formation. These findings identify catharanthine as a promising preclinical β-lactam adjuvant candidate and support further pharmacological and translational evaluation against MRSA infections.