Antimicrobial activity of essential oils against pathogens isolated from Bovine Mastitis

Treatments for bovine mastitis based on antibiotic therapy are not always effective which may lead to faults in recovery of diseased animals, selection of resistant bacteria and the presence of antimicrobial residues in milk. In this context the use of essential oils configures as an alternative to control mastitis pathogens in dairy cows because they have antibacterial action against gram-positive and gram-negative bacteria and no diverse effects on human health. The objective of this study was to determine, by the method of broth microdilution, the minimum inhibitory concentration (MIC) of essential oils of Salvia sclarea, Eugenia caryophyllata, Thymus vulgaris, Cymbopogon winterianus, Elettaria cardamomun, Cymbopogon flexuosus, Rosmarinus officinalis and Cinnamomum cassia for isolates of Staphylococcus aureus and Streptococcus agalactiae associated with clinical and subclinical mastitis. C. cassia, T. vulgaris, C. flexuosus, E. caryophyllata, C. winterianus essential oils presented high antibacterial action against both the pathogens. The S. sclarea and R. officinalis oils did not show significant antibacterial activity against both the microorganisms. High synergism in antimicrobial action against S. aureus and S. agalactiae was observed in the combination of C. cassia, C. flexuosus and E. caryophyllata essential oils. Moderate synergism in antimicrobial effect was also observed in associations involving the C. cassia essential oil. The results indicated the prospect of using essential oils to control bovine mastitis caused by S. aureus and S. agalactiae.