In vitro Antibacterial Activity of Herbal Medicines and Combinations of Herbal Medicines and Antibiotics against Edwardsiella tarda

Abstract

The antibacterial activity of five medicinal herbs, alone and together with other herbs or one of six antibiotics, against Edwardsiella tarda was determined by World Health Organization-International Collaborative Study (WHO-ICS) agar dilution protocol. Minimal inhibitory concentrations (MIC) of the herbs were significantly lower (≤4 mg/ml) in treatments using the combinations Rhizoma coptidis+Radix scutellariae, Galla chinensis+Radix et Rhizoma rhei, Galla chinensis+Radix scutellariae, and Radix et Rhizoma rhei+Radix scutellariae than in treatments using Rhizoma coptidis, Radix et Rhizoma rhei, or Flos lonicerae (≥32 mg/ml). Almost all the combination treatments were more effective than treatment by a single herb. Combinations containing herbal medicines and regular antibiotics resulted in varying results: antibacterial effects increased with some combinations and decreased with others. Galla chinensis is suitable for use with most antibiotics, while streptomycin sulfate is suitable for use with many herbal medicines.