Exploiting strong synergies between punicalagin and cefoperazone to combat methicillin-resistant Staphylococcus aureus infections.

Methicillin-resistant Staphylococcus aureus (MRSA) represents a serious public health threat. The effectiveness of existing antibiotics to treat MRSA infections is diminishing. This study aims to develop novel antimicrobial alternatives to fight MRSA infections. We conducted an anti-virulence screening targeting the L-lectin module (SLL) of the S. aureus cell wall protein serine-rich adhesin for platelets (SraP) against a database consisting of >14,000 natural products. The top candidates identified, including the polyphenol punicalagin (PA), were validated using surface plasmon resonance and a range of microbiological assays, including cell adhesion and invasion, biofilm formation, checkboard assays, microbiome studies, and RNAseq, for their properties to combat MRSA. The efficacy of punicalagin in treating MRSA infections, alone or in combination with existing antibiotics, was investigated using mouse models. PA was bound to the virulence factor SraP with high affinity and was highly effective in inhibiting MRSA colonization. PA significantly reduced the expression of multiple genes associated with ß-lactam resistance and disrupted biofilm formation. The synergistic effects between PA and cefoperazone (CF), a well-known bactericidal, were remarkable. The combination of PA and CF reduced the bacterial load in key murine organs by >98.9% and completely protected mice infected by MRSA. PA restored native gut microbiota disrupted by antibiotics, enriched butyrate-producing species, and repressed tissue inflammation. PA acted as a potent anti-virulence agent in addition to its intrinsic anti-inflammatory properties. Taking advantage of the strong synergism between PA and CF represents a promising strategy for combating MRSA infection and antibiotic resistance.