In vitro antibacterial activity of several plant extracts and essential oils against Brucella melitensis
Medicinal plants are considered to be new resources for the production of agents that could act as alternatives to antibiotics in the treatment of antibiotic-resistant bacteria. The aim of this study was to evaluate the efficacy of some plants native to Syria in the treatment of brucellosis. In vitro activities of some essential oils and plant extracts of some medicinal plants against 89 Brucella melitensis isolates was determined by disc diffusion method at a concentration of 5%. The microdilution assay in the fluid medium was used to determine the MICs of essential oils and plant extracts. Among the evaluated herbs, only Thymus syriacus and Cinnamomum zeylanicum essential oils and Laurus nobilis plant extract showed a high activity against B. melitensis strains. Thus, minimal inhibitory concentration (MIC50) values for T. syriacus, C. zeylanicum, and L. nobilis against B. melitensis were 6.25, 3.125 and 6.25 μl/ml, respectively. Among studied essential oils and plant extracts, T. syriacus and C. zeylanicum essential oils, and L. nobilis plant extract were the most effective ones. Moreover, T. syriacus - C. zeylanicum combination was more effective than use of each of them alone. Then, T. syriacus and C. zeylanicum essential oils and L. nobilis plant extract could act as bactericidal agents against B. melitensis.