In Vitro Synergy of Extract in Combination with Antibiotics for Inhibiting and Killing Methicillin-Resistant .

Aims: Currently, we face the serious problem of multiple drug-resistant pathogens. The development of new antimicrobial agents is very costly and time-consuming. Therefore, the use of medicinal plants as a source of alternative antibiotics or for enhancing antibiotic effectiveness is important.

Methods: The antibacterial effects of aqueous extracts of the seed coat of (Linn.) Pierre in combination with several antibiotics against methicillin-resistant (MRSA) were tested by broth dilution, checkerboard, and time-kill methods.

Results: For the combinations of with ampicillin, meropenem, cefazolin, cefotaxime, cefpirome, and cefuroxime, 70% to 100% were synergistic, with a fractional inhibitory concentration (FIC) index of < 0.5. For the time-kill method with 0.5× minimum inhibitory concentration (MIC) of in combination with 8, 4, 2, and 1 µg mL of the various antibiotics, almost all of the combinations showed synergistic effects, even with the lowest concentrations of , except for aztreonam. No antagonistic effect was observed for these combinations.

Conclusions: Based on these findings, aqueous seed coat extracts of have good potential for the design of new antimicrobial agents.