Investigation of antibacterial activity of essential oil from arial part of Achellia millefolium against some gram-positive bacteria isolated from bovine mastitis in Shahrekord district

Mastitis is one of the major diseases of dairy cows throughout the world which is associated with severe economic losses for dairy producer. Antimicrobial resistance, production of secondary harmful metabolites and drug residues in animal products following use of antibiotics are shifting interests of clinicians into the use of medical plants. The aim of present study was to evaluate in-vitro antibacterial activity of Achillea essential oil extract against some gram positive bacteria isolated from cases of bovine mastitis in Shahrekord. Essential oil was obtained by Clevenger apparatus according to British pharmacopeia protocol. The chemical composition was analyzed by GC/MS. Disk diffusion and macro dilution methods were used for the determination of antibacterial activity. Disk diffusion method showed that the essential oil in concentrations of 5mg/mL may inhibit all bacterial growth. Macro dilution test revealed that for Streptococcus agalactiae, Streptococcus dysgalactiae, and Enterococcus faecalis, the MIC and MBC were 4.73 mg/mL and 9.46 mg/mL, respectively. The MIC and MBC of Staphylococcus aureus were 4.73 mg/mL and 2.365mg/mL, respectively. According to the results, it was concluded that essential oil of Achillea extract might be used in vitro as a bactericidal agent for the bacteria that cause mastitis.