Chemical profile and bacterial potential of Psidium cattleyanum leaf extract against multidrug-resistant Staphylococcus aureus

Abstract The increasing prevalence of multidrug-resistant (MDR) Staphylococcus aureus represents a major challenge for global public health and highlights the urgent need for new antimicrobial strategies. In this context, plant-derived compounds have emerged as promising sources of bioactive molecules with antimicrobial and antivirulence potential. The present study investigated the phytochemical profile and antimicrobial properties of a hydroalcoholic leaf extract of Psidium cattleyanum against reference and multidrug-resistant S. aureus strains. Phytochemical analyses revealed the presence of bioactive metabolites, particularly flavonoids and ellagic acid derivatives. Antimicrobial activity was evaluated through minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays, as well as growth curve analysis. The extract inhibited all tested strains, with MIC values ranging from 128 to 256 µg/mL and MBC values between 256 and 512 µg/mL. Additionally, the extract significantly reduced important virulence factors of S. aureus , including hemolytic activity and staphyloxanthin production. Synergistic interactions were also observed when the extract was combined with ciprofloxacin or gentamicin, markedly enhancing the antibacterial activity of both antibiotics. These findings indicate that P. cattleyanum contains bioactive compounds capable of inhibiting bacterial growth and attenuating virulence mechanisms in S. aureus , highlighting its potential as a source of natural agents for the development of alternative or adjunctive antimicrobial therapies against resistant pathogens.