Synergistic activity of Ginsenoside Rh2 with β -lactam antibiotics and its mechanism of action against methicillin-resistant Staphylococcus aureus

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) presents a significant threat to public health owing to its high pathogenicity and multidrug resistance. The use of antibiotic combinations, including antibiotics and antibiotic adjuvants, has proven effective in treating drug-resistant bacterial infections. This study evaluated the antibacterial effects of Ginsenoside Rh2 (G-Rh2) combined with β -lactam antibiotics against MRSA and investigated the underlying mechanisms. Checkerboard assays revealed that G-Rh2 and β -lactam antibiotics (cefoxitin, cefazolin, ampicillin, and meropenem) exhibit a synergistic antibacterial effect on MRSA. Bacterial growth curves showed that the combination of 12.5 μg/mL G-Rh2 and sub-MIC β -lactam antibiotics effectively inhibited bacterial growth within 24 h. Morphological observation and measurement of intracellular component leakage indicated that the combination of G-Rh2 and cefoxitin (CFX) synergistically compromised the integrity of MRSA cell membranes. G-Rh2 alone had an anti-biofilm effect, and when combined with CFX, it exhibited a synergistic effect. The combination could significantly inhibit the formation of biofilms and eradicate mature biofilms. To elucidate the molecular basis of the synergistic antibacterial effect, transcriptomic analysis was performed. The data demonstrated that the synergy correlates with the downregulation of vraR and genes within the dlt and pst operons. Collectively, our results demonstrate that the combination of G-Rh2 and β -lactam antibiotics represents a promising therapeutic strategy against MRSA infections. IMPORTANCE Methicillin-resistant Staphylococcus aureus (MRSA) is a formidable pathogenic bacterium capable of causing severe infections. This multidrug-resistant organism exhibits resistance to β -lactam antibiotics, including penicillins, cephalosporins, and carbapenems. This study reveals that the natural compound Ginsenoside Rh2 (G-Rh2) can restore the susceptibility of MRSA to these antibiotics. When used in combination, G-Rh2 and β -lactam antibiotics exhibit synergistic antibacterial activity, leading to compromised cell membrane integrity and disruption of biofilms. Moreover, G-Rh2 significantly delays the development of antibiotic resistance. These findings provide a promising new strategy for using natural products to combat antibiotic-resistant infections, which may extend the lifespan of existing antibiotics and improve the treatment outcomes for patients.