OBJECTIVES:

In this study we examined the in vitro synergistic effect of baicalin, the flavone constituent of Scutellaria spp., in combinations with oxytetracycline and tetracycline on the growth of Staphylococcus aureus.

METHODS:

The MICs were determined by the broth microdilution method and the effect of combinations was evaluated according to the sum of fractional inhibitory concentration indices (FICIs).

RESULTS:

Synergistic activity (FICI  ≤  0.5) was observed for combinations of baicalin with oxytetracycline or tetracycline against 4 of 10 strains tested, whereas the baicalin/oxytetracycline combination possessed the strongest synergistic effect (FICI = 0.418).

CONCLUSIONS:

Baicalin acts synergistically with oxytetracycline and tetracycline, enhancing its antimicrobial activity against S. aureus, including methicillin- and tetracycline-resistant strains.