Chemotherapy: Open Access
Open Access

Abstract

Synergistic Effect between Baicalein and Antibiotics against Clinic Methicillin and Vancomycin-Resistant Staphylococcus aureus

Young-Soo Lee, Eun-Kyung Jung and Jeong-Dan Cha

Baicalein is one of the major flavonoids in Scutellaria baicalensis Georgi, which has long been used in several biological effects, such as antiviral, anti-inflammation, anti-hepatotoxicity, and anti-tumor properties, have been reported. In this study, baicalein demonstrated strong antibacterial activity against clinic isolated methicillin and vancomycin-resistant Staphylococcus aureus (MRSA and VRSA) in this experiment. Baicalein was determined against clinic isolated MRSA 1-16 with MIC and MBC values ranging from 64 to 256 and 64 to 512 μg/ml; for MSSA 1-2 from 128 and 256 μg/ml and 128 and 512 μg/ml; for VRSA 1-2 from 64 and 128 μg/ml and 64 and 512 μg/ml, respectively. The range of MIC50 and MIC90 of baicalein were 16-64 μg/ml and 64-256 μg/ml, respectively. The combination effects of baicalein with antibiotics were synergistic (FIC index <0.5) against most of tested clinic isolated MRSA, MSSA, and VRSA except additive, MRSA 7 in oxacillin and MRSA 8 and 15 in vancomycin (FIC index <0.625-0.75). Furthermore, a time-kill study showed that the growth of the tested bacteria was completely attenuated after 2-6 h of treatment with the ½ MIC of baicalein, regardless of whether it was administered alone or with ampicillin, oxacillin, or vacomycin. The results suggest that baicalein could be employed as a natural antibacterial agent against multidrug-resistant pathogens infection.