Combination Therapy of Sophoraflavanone B against MRSA : In Vitro Synergy Testing

الملخص EN

Sophoraflavanone B (SPF-B), a known prenylated flavonoid, was isolated from the roots of Desmodium caudatum.

The aim of this study was to determine the antimicrobial synergism of SPF-B combined with antibiotics against methicillin-resistant Staphylococcus aureus (MRSA).

MRSA, a multidrug-resistant pathogen, causes both hospital- and community-acquired infections worldwide.

The antimicrobial activity of SPF-B was assessed by the broth microdilution method, checkerboard dilution test, and time-kill curve assay.

The MIC of SPF-B for 7 strains of S.

aureus ranges from 15.6 to 31.25 μg/mL determined.

In the checkerboard method, the combinations of SPF-B with antibiotics had a synergistic effect; SPF-B markedly reduced the MICs of the β-lactam antibiotics: ampicillin (AMP) and oxacillin (OXI); aminoglycosides gentamicin (GET); quinolones ciprofloxacin (CIP) and norfloxacin (NOR) against MRSA.

The time-kill curves assay showed that a combined SPF-B and selected antibiotics treatment reduced the bacterial counts below the lowest detectable limit after 24 h.

These data suggest that the antibacterial activity of SPF-B against MRSA can be effectively increased through its combination with three groups of antibiotics (β-lactams, aminoglycosides, and quinolones).

Our research can be a valuable and significant source for the development of a new antibacterial drug with low MRSA resistance.